Volume 16, Number 9/10
Table of Contents
Representation and Recognition of Subject Repositories
University of Massachusetts Amherst
University of Massachusetts Amherst
Subject repositories are under-studied and under-represented in library science literature and in the scholarly communication and digital library fields. A study of practical literature on subject repositories reveals a relatively small proportion of practical articles to total articles found that discuss subject repositories in some way where practical refers to articles that would help inform decisions on repository development and management. In addition to the lack of practical literature on subject repositories, registries, software, publishers, and database thesauri do not define subject repositories consistently, do not recognize subject repositories as distinct from other types of repositories, or do not recognize subject repositories at all. At the same time, subject repositories are frequently cited as highly successful scholarly communication initiatives, especially in relation to institutional repositories. The lack of subject repository recognition within the literature and among commonly used repository tools may be attributed to the isolated development of the largest subject repositories and a general lack of awareness about small-scale subject repositories. The authors recommend an increase of literature and research on subject repositories, development of standard language, guidelines, and best practices, and the formation of a community of subject repository professionals.
Subject repositories repositories that collect and provide access to the literature of a single subject or a set of related subjects are often cited as highly successful scholarly communication initiatives, especially in relation to institutional repositories. Despite their purported success, there is little literature on the work involved in developing and managing a subject repository. Instead, an abundance of literature exists on general profiles of subject repositories,[n1] impact studies based on their use or functionality,[n2] increased citation rates for articles deposited in arXiv,[n3] the NIH PubMed Central depositing mandate,[n4] and general discussions of open access trends in relation to repositories.[n5] In addition to the lack of practical literature, registries, software, publishers, and database thesauri do not generally define subject repositories in the same way, or recognize them at all.
Representation and recognition of subject repositories in the field of library science is essential for the creation of best practices and standards, which will promote informed development. The authors manage two small-scale subject repositories at the University of Massachusetts Amherst: InterNano (NSF CMMI 0531171) is a nanomanufacturing resource and the Ethics in Science and Engineering National Clearinghouse, or ESENCe, (NSF SES 0936857) is a resource for the responsible conduct of research in science and engineering disciplines. While developing these repositories, the need for literature and representation in the field was identified and is presented in this article as a first step towards the realization of standards and documentation for subject repositories. A study of current practical literature on subject repositories is described, accompanied by a status report on the representation of subject repositories in registries, software, publishers, and database thesauri.
Study of Practical Literature on Subject Repositories
While there are challenges associated with finding literature on subject repositories, it is important to document the nature of this literature in order to identify trends and gaps, which can inform further research. Practical discussions of subject repositories in general and discussions about the development and management of the ten most populated subject repositories are analyzed. The repositories were identified by comparing data between Open DOAR (Directory of Open Access Repositories), ROAR (Registry of Open Access Repositories), and Ranking Web of World Repositories (RWWR), three sites that index and track open access repositories. The repositories selected host English-language scholarly documents such as pre-prints or post-prints, are subject, disciplinary, or multi-disciplinary, and are national or international in scope. Institutional repositories, archives, image collections and strict data collections were excluded. The following subject repositories were identified as the ten most populated and are the subjects of this study: PubMed Central, CiteSeerx[n6], Research Papers in Economics (RePEc), arXiv, Social Science Research Network (SSRN), AgEcon Search, Policy Archive, Archive of European Integration (AEI), E-prints in Library and Information Science (E-LIS), and Organic EPrints.
Peer-reviewed English-language articles written since 2000 that address the development or management of subject repositories were identified by searching academic databases with library and information science coverage. As there is no database thesaurus that includes controlled vocabulary for subject repositories,[n7] searching was utilized to identify materials. The citations were then manually reviewed to eliminate articles that did not fit into the scope of the study. The authors used "What would help a subject repository manager make practical decisions about technical infrastructure, organizational models, or policy development?" as a guiding question for the selection of articles.[n8]
General Practical Literature on Subject Repositories
Six articles were identified that make general recommendations about subject repositories (See Table 1). All but one article (Qing and Ruhua, 2008) discuss subject repositories in relation to institutional repositories.[n9] All general articles were written since 2002, and they all focus on different subject repository issues: usability, stakeholder roles in development and organization, name metadata, user groups, interactions between different types of repositories, and content recruitment, preservation, and discovery. Therefore, there are no topic trends identified in the general literature. However, several of the articles use specific subject repositories as illustrations. Five of the articles discuss arXiv (Qing and Ruhua, 2008; Solla, 2002; Xia, 2006; Darby et al., 2008; Xia, 2008), two discuss PubMed Central (Qing and Ruhua, 2008; Xia, 2008), two discuss E-LIS (Qing and Ruhua, 2008; Xia, 2006), two discuss RePEc (Xia, 2006; Darby et al., 2008), and one article does not discuss any of the top ten subject repositories (Peters, 2002).
||Subject Repositories Discussed
||Subject repositories in the context of scholarly communication
|Qing and Ruhua
||PubMed Central, E-LIS, arXiv
||arXiv, E-LIS, RePEc
||Stakeholder roles in development and organization
||User-generated author name metadata
|R.M. Darby et al.
||arXiv, RePEC, UKPMC, ESRC Society Today
||Interactions between institutional, subject, and founder repositories. Content recruitment, preservation, and discovery
||User groups, subject vs. institutional repositories
Table 1: General Articles on Subject Repositories
Practical Literature on the Top Ten Repositories
31 articles were found that discuss the ten largest subject repositories in a practical way (See Table 2). These articles have overwhelmingly been written by repository mangers or affiliates and come in the form of historical development, software development overviews, or descriptions of local policies and workflows. Where the authors have been involved in the technical development of the repository, the articles tend to be more technological and describe the elements of infrastructure in some detail. Where authors have been repository managers or board members, the articles tend to focus on organizational, policy and collection development, or sustainability issues. For example, the majority of the seven papers on RePEc include a technical section and most of those articles have been written by Thomas Krichel, the primary architect of the repository.[n10] All of the CiteSeerx papers focus on the technical infrastructure and were written by development team members. In contrast, PubMed Central has no papers that cover the repository's technical infrastructure and has few papers that go into other details of its management; the majority of papers focus on the political environment of PubMed Central and were authored by PubMed Central board members or unaffiliated librarians.
There is no significant correlation between the number of records in a repository and the number of articles written about the development and management of a repository. However, when all topics are included, there are significantly more articles written about the most populated repositories than the lesser populated ones. The exception to this trend is E-LIS. These repositories, including E-LIS, are those most typically used as examples of the success or successful impact of subject repositories in the general literature. PubMed Central is the most notable with regard to the amount of literature describing its role and impact on scholarly communication.
The most important observation of practical, published literature is the small proportion of practical articles that inform subject repository development against the total results of the exhaustive article search. Most of the remaining articles can be seen as falling into four major categories: analysis of researcher behaviors (including citation analysis), Open Access impact, subject literature reviews, and reviews or editorials. While these articles are certainly informative, they do not contribute to overarching best practices for subject repository development or help a subject repository manager make decisions about technical infrastructure, organizational models, or policy development.
|Archive of European Integration
Table 2: Top Ten Subject Repositories and Literature Counts
Representation of Subject Repositories in Commonly Used Repository Tools
In the process of evaluating the literature on subject repositories, it quickly became evident that there was an overarching lack of representation of subject repositories across many commonly used tools for repository development, management, and content acquisition.
One of the biggest technical decisions a repository manager has to make is the selection of appropriate software. There is no software that is explicitly designed for subject repositories, but there is repository software that is explicitly designed for institutional repositories, such as bepress Digital Commons and VITAL, which are both hosted software services. DSpace is the only software that specifically mentions subject repositories in its documentation, while the other major software platforms (EPrints, Fedora, Open Repository, Content DM, and Greenstone) provide general repository or digital collection language. While open source repository software is highly customizable, it should be clear upfront which repository software is the most effective for different types of repository environments. Both subject repositories and institutional repositories benefit from discoverability through search engines like Google Scholar and WorldCat, but subject repositories are more often construed as destination sites (the most apparent examples are PubMed or arXiv). As a result, subject repositories may require more dynamic browse features and tools for user personalization compared to institutional repositories.
The two main registries that track information about subject repositories are OpenDOAR (Directory of Open Access Repositories) and ROAR (Registry of Open Access Repositories). OpenDOAR and ROAR do not collect the same type of information, do not define subject repositories in the same way, and do not provide explanations of how the repositories indexed are categorized. OpenDOAR classifies repositories as aggregating, disciplinary, governmental, and cross-institutional, and includes subject area search functionality. It documents the homepage link, host organization, repository description, size (number of records), subject coverage, content types, languages supported, and policies. ROAR defines repositories as database/abstracting & indexing index, demonstration, learning and teaching objects, research cross-institutional, research institutional or departmental, e-journal/publication, e-theses, and other, and documents description, homepage, repository type, software, country, location, "birth date," record count, a history of record counts, daily deposit activity, an OAI-PMH interface link, links to the repository in other registries, and provides a graph documenting the number of records by year.
Both OpenDOAR and ROAR provide aggregations of valuable information, but they define repositories in such different ways and do not define how the repositories are classified. As a result, it is difficult to identify repositories that are similar in scope, conduct research on subject repositories, and make generalizations about subject repository trends. It is difficult to know how many subject repositories exist because of the undocumented definitions, but generally speaking, there are between 150-400 subject repositories registered in OpenDOAR and ROAR. While literature about subject repositories often cites PubMed Central, RePEc, and arXiv as examples of successful subject repositories, there are actually hundreds of smaller-scale subject repositories that have been funded and are actively collecting materials. OpenDOAR and ROAR are rich with information about subject repositories, and with some standardization of naming in the field, these resources can contribute to wider-reaching studies of all types and sizes of subject repositories.
Copyright and Author Self-archiving Policies
Because of a smaller user base and lack of name recognition, the smaller repositories often have to engage in active collection development. This will almost certainly include marketing the repository to potential authors, who may not have a thorough understanding of their author and self-archiving rights. The Sherpa/RoMEO database is a resource that clearly indicates publisher copyright and author archiving policies for repositories, author websites, and personal use. Most records in the database indicate self-archiving policies for institutional repositories, funder repositories, and personal websites, but not for third party sites. Some Sherpa/RoMEO records indicate that publishers allow an author to archive their work on a "non-profit server," but this is a rare case. The rarity of "non-profit server" specification indicates either conservative publisher policies or a lack of publisher awareness about the possibility of archiving in a non-funder subject repository. If a publisher has very liberal author self-archiving policies, it will not dictate archiving platform, but will list, for example, a publisher acknowledgement requirement or article version requirements. Authors that publish in journals with more conservative copyright policies have to contact the publisher or acquire a license via Copyright Clearance Center's Rightslink to post their work in a subject repository, a major deterrent to self-archival. A lack of recognition of the potential to self-archive an article in a non-funder subject repository limits the collecting capacity of a subject repository, and therefore limits a subject repository's reach in its field.
Terminology and Database Thesauri
Finding relevant literature on subject repositories is a real challenge because many subject repositories are named something other than a repository, such as clearinghouse, digital library, and digital archive. These terms are not mutually exclusive for library resources. For example, a search on "digital library" may return articles that discuss digital image collections. The lack of agreement on a common word for subject repositories is almost certainly due to marketing and presenting a less static-sounding service to users, and this is understandable. However, it makes it difficult to search for literature.
To further complicate the issue, discovering literature on subject repositories through controlled vocabulary is currently impossible because no library science database features controlled vocabulary for subject repositories. E-LIS uses the term "repositories", Library and Information Science Abstracts and Library, Information Science & Technology Abstracts have controlled vocabulary only for institutional repositories, and Library Literature and Information Science Full Text does not have any controlled vocabulary for any type of repository. Lack of agreed terminology and controlled vocabularies for subject repositories contributes to severe restrictions for identifying literature on subject repositories.
It is clear that the literature on the development and management of subject repositories is not mature, which is surprising, given that five top populated repositories were established by 2000. As a point of reference, 470 peer reviewed articles since 2000 exist that include "institutional repository*" in the title or abstract, compared with 16 articles with "subject repository*" in the title or abstract, which is 29 times less. The only broad evaluations of subject repositories are framed in relation to other subject repositories, or in relation to institutional repositories. It is thus difficult to understand the full impact that subject repositories have had on their respective fields, as well as the impact subject repositories have on larger scholarly communication and digital library issues as distinct from institutional repositories. Nor is it easy to see their utility in relation to other technologies or services that would assist in the preservation and dissemination of research.
There is also a lack of literature on the ten identified subject repositories. The literature reviewed reveals little interaction between subject repository managers and developers. These repositories have grown in relative isolation from one another, in a specific disciplinary context: PubMed Central has a National Institutes of Health depositing mandate, arXiv comes out of a pre-existing disciplinary culture of sharing pre-prints in physics, CiteSeerx leverages computer science to extend its collection and dissemination services, and E-LIS is a product of the self-aware and referential field of library science. These repositories should be studied to identify subject repository trends that could be generalized and applied to other subject repositories. Repository managers and affiliates are best positioned to write about local practices due to their close work with their repositories. However, non-affiliates could write general literature and conduct evaluations of existing repositories to further the field.
There is also a noted lack of representation and recognition of subject repositories in some of the most valuable tools for scholarly communication work. There are several important consequences of this trend: it is difficult for repository managers to make informed decisions about repository development, it is difficult to conduct research on subject repository trends, and it is difficult for authors to understand and navigate their rights as authors if they want to self-archive in a subject repository. The lack of representation and recognition of subject repositories in these tools may come from a shortage of knowledge about the smaller subject repositories, and the practice of identifying only large subject repositories as examples of successful scholarly communication initiatives may contribute to the distortion of the subject repository landscape. This reinforces recognition of only a small number of existing subject repositories.
While the huge impact and success of the large subject repositories should be recognized, it is also important to acknowledge the hundreds of subject repositories that do exist and to understand that this mass of repositories also fits in the scholarly communication conversation.
In light of the lack of representation and recognition in literature and standard scholarly communication tools outlined above, the authors make the following recommendations.
1.) An increase of literature and research
Subject repositories are valuable to researchers, institutions, and funding organizations as producers and consumers of research (R.M. Darby et al., 2008). If subject repositories are to continue to take on the responsibility of capturing and disseminating disciplinary output, then many more detailed articles on the development, management, and best practices for subject repositories as distinct entities from institutional repositories are needed. More articles should take a wider scope on management and development issues and draw conclusions that will serve the community of subject repository managers. Many repository managers author case studies, which are very informative, but it is also important to examine subject repositories from a higher-level perspective. A broader perspective can offer guidance whereas a case study often points to a single example of a particular implementation.
2.) Standard language for subject repositories
Standard digital library and scholarly communication resources, software vendors, professional associations, publishers, and those in the library and information science field should recognize and share a common understanding of subject repositories and related terminology. With this standardization, repository managers could easily seek guidance from these resources, research could be conducted with more reliability, and authors and users of subject repositories would benefit through clearer policies.
3.) Guidelines and best practices
Because repositories of all types are continuing to grow at a larger rate with each year, more defined guidelines and best practices should be developed for repositories. But it is most important that subject repositories should not have to rely on guidelines created for institutional repositories, as they are very different in purpose.
4.) A community of subject repository professionals
A community of interest for subject repositories would be useful for answering questions and engaging discussion on problems faced by repository managers. A listserv would be a strong platform, and events that focus on subject repositories could provide a forum for repository managers to network and exchange ideas. In January 2010, a Subject Repositories conference was held in London to launch a new subject repository service and portal, Economists Online. This event is a great start, and similar large-scale events, in addition to sub-tracks at larger conferences and regional small-scale events are encouraged.
Funding for this project comes from the National Science Foundation through grant numbers 0936857 and 0531171. Any opinions, findings, conclusions or recommendations expressed here are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
[n1] Hey & Hey, 2006; McKiernan, 2002; Ramlo, 2007
[n2] Larivière, Archambault, & Gingras, 2008; Feitelson & Yovel, 2004
[n3] Brody, Harnad, & Carr, 2006; Brown, 2001; Davis & Fromerth, 2007; Haque & Ginsparg, 2009; Henneken et al., 2006; Kurtz et al., 2005; Moed, 2007
[n4] Gass, 2004; Schwartzkroin & Shorvon, 2008; Zerhouni, 2004
[n5] Morris & Thorn, 2009; Richardson, 2005; Rowland, 2005; Wani, Gul, & Rah, 2009
[n6] CiteSeerx currently stores and makes available cached versions of all indexed documents, with their associated metadata, qualifying it as a repository.
[n7] See the section "Terminology and Database Thesauri."
[n8] Detailed methodology for the study of literature:
Academic Search Premier, E-LIS, ERIC (Education Resources Information Center), Google Scholar, Library Literature and Information Science Full Text, LISA: Library and Information Science Abstracts, LISTA: Library, Information Science & Technology Abstracts, PsychINFO, Sociological Abstracts, and Web of Science were searched. For general literature about subject repositories, the following search strategy was used: ("subject repositor*" OR "subject-based repositor*" OR (repositor* AND subject) OR (digital library AND subject) OR (digital library AND discipline)). This search was applied to the title and abstract fields for each database.
To identify literature on the top ten subject repositories, the following search strategy was used: "pubmed central*" OR citeseer* OR repec* OR arxiv* OR ssrn* OR "social science research network*" OR "agecon search*" OR "policy archive*" OR "archive of european integration*" OR AEI* OR E-LIS* OR "Organic eprints*". This search was also applied in the title and abstract fields for each database. Finally, using the title and abstract fields, each subject repository was searched for literature on itself. For example, E-LIS was searched for literature on E-LIS.
When searching for literature on arXiv, a large number of abstracts extracted by Academic Search Premier include references to arXiv-archived articles. As a result, only a title search for arxiv* in Academic Search Premier was completed. Google Scholar was not searched for literature about arXiv because the search engine returns thousands of citations with arXiv numerical identifiers. Neither Google Scholar nor Web of Science has abstract searching functionality, so a title search only was conducted for Google Scholar and a title and topic search was conducted for Web of Science.
[n9] A recent working paper by Armbruster and Romary (2009), compares the challenges faced by four different repository types in an effort to determine which type best supports scholarly communication.
[n10] Additional papers that did not match the criteria for literature review yet would be useful to a repository manager include: Krichel (2000); Krichel and Warner (2001); Cruz, Krichel & Trinidad (2003); Parinov & Kritchel (2004).
 Armbruster, C. & Romary, L. (2009). Comparing repository types: Challenges and barriers for subject-based repositories, research repositories, national repository systems and institutional repositories in serving scholarly communication (November 23, 2009). Retrieved from SSRN: http://ssrn.com/abstract=1506905.
 Bakkalbasi, N., & Krichel, T. (2005). Developing a predictive model of editor selectivity in a current awareness service of a large digital library. Library & Information Science Research 27, 440 - 452. doi:10.1016/j.lisr.2005.08.003
 Bray, David A., Vitzthum, Sascha and Konsynski, Benn. SSRN as an Initial Revolution in Academic Knowledge Aggregation and Dissemination (January 7, 2008). Retrieved from SSRN: http://ssrn.com/abstract=1081478.
 Brody, T., Harnad, S., & Carr, L. (2006). Earlier web usage statistics as predictors of later citation impact. Journal of the American Society for Information Science and Technology, 57(8), 1060-1072. doi:10.1002/asi.20373
 Brown, C. (2001). The coming of age of E-prints in the literature of physics. Issues in Science and Technology Librarianship, 31.
 Chu, H., & Krichel, T. (2003). NEP: Current Awareness Service of the RePEc Digital Library. D-Lib Magazine, 9(12). doi:10.1045/december2003-chu
 Councill, I. G., Giles, C. L., Di Iorio, E., Gori, M., Maggini, M., & Pucci, A. (2006). Towards next generation CiteSeer: A flexible architecture for digital library deployment. Lecture Notes in Computer Science. (4172), 111-122. doi:10.1007/11863878_10
 Cruz, J. M. B., & Krichel, T. (2000). Cataloging Economics Preprints: An Introduction to the RePEc project. Journal of Internet Cataloging 3(2/3), 227-242.
 Cruz, J. M. B., Krichel, T., & Trinidad J. C. (2003). Organizing current awareness in a large digital library. In Conference on Users in the Electronic Information Environments, Espoo, Finland, September 8 - 9.
 Darby, R. M., Jones, C. M., Gilbert, L. D., & Lambert, S. C. (2008). Increasing the productivity of interactions between subject and institutional repositories. New Review of Information Networking, 14(2), 117-135. doi:10.1080/13614570903359381
 Davis, P. M., & Fromerth, M. J. (2007). Does the arXiv lead to higher citations and reduced publisher downloads for mathematics articles? Scientometrics, 71(2), 203-215. doi:10.1007/s11192-007-1661-8 ER
 DeRobbio, A., & Katzmayr, M. (2009). The management of an international open access repository: the case of E-LIS. GMS Med Bibl Inf, 9(1), Doc09.
 DeRobbio, A., & Subirats Coll, I. (2005). E-LIS: an international open archive towards building open digital libraries. High Energy Physics Libraries Webzine 11.
 Duncan, S. (2008). Demystifying the SSRN Process: How to Make it Work for You (July 21, 2008). Retrieved from SSRN: http://ssrn.com/abstract=1166022.
 Feitelson, D. G., & Yovel, U. (2004). Predictive ranking of computer scientists using CiteSeer data. Journal of Documentation, 60(1), 44.
 Feng, Q., & Huang, R. (2008). Evaluating the usability of discipline repositories. IEEE International Symposium on IT in Medicine and Education, 2008. ITME 2008, 385-390. doi:10.1109/ITME.2008.4743892
 Fischel, M., & Myers, C. J., (2007). The PubMed Central archive and the back issue scanning project. Journal of Interlibrary Loan, Document Delivery & Electronic Reserve 17(3), 109 - 116. doi:10.1300/J474v17n03_14
 Gass, A. (2004). Open access as public policy. PLoS Biology, 2(10), 1495-1495. doi:10.1371/journal.pbio.0020353
 Gunnarsdóttir, K. (2005). Scientific journal publications: On the role of electronic preprint exchange in the distribution of scientific literature. Social Studies of Science, 35(4), 549-579. doi:10.1177/0306312705052358
 Haque, A. U., & Ginsparg, P. (2009). Positional effects on citation and readership in arXiv. Journal of the American Society for Information Science and Technology, 60(11), 2203-2218. doi:10.1002/asi.21166 ER
 Henneken, E. A., Kurtz, M. J., Eichhorn, G., Accomazzi, A., Grant, C., Thompson, D., & Murray, S. S. (2006). Effect of e-printing on citation rates in astronomy and physics. JEP: The Journal of Electronic Publishing, 9(2). doi:10.3998/3336451.0009.202
 Homan, J. M., & Watson, L. A. (2004). STM publishing meets NIH digital archive: librarian service on the PubMed Central National Advisory Committee. Reference Services Review 32(1), 83 - 88.
 Hey, T., & Hey, J. (2006). E-science and its implications for the library community. Library Hi Tech, 24(4), 515-528. doi:10.1108/07378830610715383
 Kelly, J., & Letnes, L. (2006). Managing the grey literature of a discipline through collaboration: AgEcon search. Resource Sharing & Information Networks, 18(1-2), 157-166.
 Kiley, R. (2006). The medical journals back-files digitization project and open access. Serials, 19(2), 95 - 102.
 Kling, R., Spector, L. B., & Fortuna, J. (2004). The real stakes of virtual publishing: The transformation of E-Biomed Into PubMed Central. Journal of the American Society for Information Science and Technology 55(2), 127 - 148.
 Krichel, T. (2000). Working toward an Open Library for Economics: The RePEc project. In PEAK Conference, Ann Arbor, MI, March 24.
 Krichel, T., & Warner, S. (2001). Disintermediation of academic publishing through the internet: An intermediate report from the front line. In Electronic Publishing '01 2001 in the Digital Publishing Odyssey. A. Hubler, et. al., Eds. IOS Press 2001. 194 - 205.
 Krichel, T., & Zimmerman, C. (2009) The Economics of Open Bibliographic Data Provision. Economic Analysis and Policy (EAP) 39(1), 143-152.
 Kurtz, M. J., Eichhorn, G., Accomazzi, A., Grant, C., Demleitner, M., Henneken, E., & Murray, S. S. (2005). The effect of use and access on citations. Information Processing & Management, 41(6), 1395-1402. doi:10.1016/j.ipm.2005.03.010
 Kumar, C. A., & Vishnu, V. (2001). PubMed Central: A phenomenal advance in electronic publishing. Current Science 81(1), 13 - 14.
 Larivière, V., Archambault, E., & Gingras, Y. (2008). Long-term variations in the aging of scientific literature: From exponential growth to steady-state science (1900-2004). Journal of the American Society for Information Science and Technology, 59(2), 288-296. doi:10.1002/asi.20744
 Letnes, L., & Kelly, J. (2002). AgEcon search: Partners build a web resource. Issues in Science & Technology Librarianship, vol. 34.
 Letnes, L., & Kelly, J. (2008b). AgEcon search: Expanding the distribution of current literature in one subdiscipline of agriculture. Agricultural Information Worldwide, 1(1), 29-29.
 Letnes, L., & Kelly, J. (2008a). AgEcon search: History and future of a collaborative subject repository. Journal of Agricultural & Food Information, 9(4), 324-328. doi:10.1080/10496500802483254
 Li, H., Councill, I. G., Bolelli, L., Zhou, D., Song, Y., Lee, W., Sivasubramaniam, A., C. Giles, C. L. (2006). CiteSeerx - a scalable autonomous scientific digital library. Conference on Scalable Information Systems.
 Li, H., Councill, I., Lee, W., & Giles, C. L. (2006). CiteSeerx: An architecture and web service design for an academic document search engine. International World Wide Web Conference, 883-884.
 Luce, R. E. (2001). E-prints intersect the digital library: Inside the Los Alamos arXiv. Issues in Science and Technology Librarianship, (29).
 McKiernan, G. (2001). RePEc: An Open Library for Economics. Library Hi Tech News 18(3).
 McKiernan, G. (2002). Scholar-based initiatives in publishing. Science & Technology Libraries, 22(3), 181-191.
 Medieros, N. (2004). A repository of our own: the E-LIS e-prints archive. OCLC Systems and Services: International Digital Library Perspectives 20(2), 58 - 60. doi:10.1108/10650750410539040
 Moed, H. F. (2007). The effect of "open access" on citation impact: An analysis of ArXiv's condensed matter section. Journal of the American Society for Information Science & Technology, 58(13), 2047-2054. doi:10.1002/asi.20663
 Morris, S., & Thorn, S. (2009). Learned society members and open access. Learned Publishing, 22(3), 221-239. doi:10.1087/2009308
 Morrison, H., et. al. (2007). E-LIS: The Open Archive for Library and Information Science. The Charleston Advisor, July 2007.
 Novarese, M., & Zimmerman, C. (2008). Heterodox economics and dissemination of research through the internet: the experience of RePEc and NEP. On The Horizon, 16(4), 198 - 204. doi:10.1108/10748120810912529
 Parinov, S. & Krichel, T. (2004). RePEc and Socionet as partners in a changing digital library environment, 1997 to 2004 and beyond. In Russian Conference on Digital Libraries, Puschchino (Russia). Available from http://eprints.rclis.org/1830/.
 Peters, T. A. (2002). Digital repositories: Individual, discipline-based, institutional, consortial, or national? The Journal of Academic Librarianship, 28(6), 414-417.
 Pope, L. (2001). PubMed Central: a barrier-free repository for the life sciences. The Serials Librarian, 40(1), 183 - 190.
 Qing, F. & Ruhua H. (2008). Evaluating the Usability of Discipline Repositories. Proceedings of 2008 IEEE International symposium on IT in Medicine and Education. 12 - 14 December 2008. doi:10.1109/ITME.2008.4743892
 Ramlo, S. (2007). ArXiv.org and physics education. Physics Teacher, 45(6), 374-375. doi:10.1119/1.2768698
 Ricciardi, V. (2007). Facilitating Research With the Social Science Research Network (SSRN): An Editor's Perspective (March 2007). Retrieved from SSRN: http://ssrn.com/abstract=928110.
 Richardson, M. (2005). Open access and institutional repositories: An evidence-based approach. Serials, 18(2), 98-103. doi:10.1629/1898
 Rowland, F. (2005). How do we provide access to the content of scholarly research information? Serials, 18(3), 218-229. doi:10.1629/18218
 Santillan-Aldana, J. (2008). The open access movement and the library world seen from the experience of the E-LIS project. OCLC Systems & Services: International Digital Library Perspectives 25(2), 135 - 147. doi:10.1108/10650750910961938
 Schwartzkroin, P. A., & Shorvon, S. D. (2008). Public (open) access policy. Epilepsia. doi:10.1111/j.1528-1167.2008.01733.x
 Smith, K. A., & Sequeira, E. (2001). Linking at the US National Library of Medicine. Learned Publishing, 14(1): 23-28. doi:10.1087/09531510125100232
 Solla, L. (2002). Building digital archives for scientific information. Issues in Science & Technology Librarianship, 36.
 Thomas, S. E. (2006). Publishing solutions for contemporary scholars: The library as innovator and partner. Library Hi Tech, 24(4), 563-573. doi:10.1108/07378830610715428
 Walshe, Emmily. (2001). Creating an academic self-documentation system through digital library interoperability: the RePEc model. New Review of Information Networking 7, 43-58.
 Wani, Z. A., Gul, S., & Rah, J. A. (2009). Open access repositories: A global perspective with an emphasis on Asia. Chinese Librarianship, (27), 6-6.
 Wilkin, P. (2009). The Archive of European Integration: Resources for European law. Legal Information Management, 9(2), 112-16. doi:10.1017/S1472669609000280
 Xia, J. (2008). A comparison of subject and institutional repositories in self-archiving practices. Journal of Academic Librarianship, 34(6), 489-95. doi:10.1016/j.acalib.2008.09.016
[63 ] Xia, J. (2006). Personal name identification in the practice of digital repositories. Program: Electronic Library and Information Systems, 40(3), 256-267. doi:10.1108/00330330610681330
[64 ] Zerhouni, E. A. (2004). NIH public access policy. Science, 306(5703), 1895-1895. doi:10.1126/science.1106929
About the Authors
Jessica Adamick is the Ethics Clearinghouse Librarian at the University of Massachusetts Amherst, where she manages the Ethics in Science and Engineering National Clearinghouse (ESENCe), a subject repository for the responsible conduct of research. She holds an MLS with a Digital Libraries Specialization from Indiana University Bloomington and a BA in Women's Studies from Earlham College.
Rebecca Reznik-Zellen is the Science Librarian for the Center for Hierarchical Manufacturing at the University of Massachusetts Amherst and manages InterNano, an information portal and subject repository for nanomanufacturing. She holds and MLIS from Simmons College and an MA in Philosophy from the Katholieke Universiteit Leuven.