  Recently, a review concluded that Google Scholar (GS) is not a suitable
source of information "for identifying recent conference papers or other gray
literature publications". The goal of this letter is to demonstrate that GS can
be an effective tool to search and find gray literature, as long as appropriate
search strategies are used. To do this, we took as examples the same two case
studies used by the original review, describing first how GS processes
original's search strategies, then proposing alternative search strategies, and
finally generalizing each case study to compose a general search procedure
aimed at finding gray literature in Google Scholar for two wide selected case
studies: a) all contributions belonging to a congress (the ASCO Annual
Meeting); and b) indexed guidelines as well as gray literature within medical
institutions (National Institutes of Health) and governmental agencies (U.S.
Department of Health & Human Services). The results confirm that original
search strategies were undertrained offering misleading results and erroneous
conclusions. Google Scholar lacks many of the advanced search features
available in other bibliographic databases (such as Pubmed), however, it is one
thing to have a friendly search experience, and quite another to find gray
literature. We finally conclude that Google Scholar is a powerful tool for
searching gray literature, as long as the users are familiar with all the
possibilities it offers as a search engine. Poorly formulated searches will
undoubtedly return misleading results.
