  In this paper we present the results of a study into the persistence and
availability of web resources referenced from papers in scholarly repositories.
Two repositories with different characteristics, arXiv and the UNT digital
library, are studied to determine if the nature of the repository, or of its
content, has a bearing on the availability of the web resources cited by that
content. Memento makes it possible to automate discovery of archived resources
and to consider the time between the publication of the research and the
archiving of the referenced URLs. This automation allows us to process more
than 160000 URLs, the largest known such study, and the repository metadata
allows consideration of the results by discipline. The results are startling:
45% (66096) of the URLs referenced from arXiv still exist, but are not
preserved for future generations, and 28% of resources referenced by UNT papers
have been lost. Moving forwards, we provide some initial recommendations,
including that repositories should publish URL lists extracted from papers that
could be used as seeds for web archiving systems.
