Journal Article Retrieval in an Age of Open Access: How Journal Indexes Indicate Open Access Articles

As the number of Open Access (OA) journal articles increases dramatically, it is time to assess how journal article indexes, both free and subscription-based, retrieve and indicate OA full text. This study uses 471 samples of OA articles to compare OA article retrieval in Google Scholar, PubMed, and Scopus, with Scopus representing subscription-based journal indexes. This study divides journal articles into two categories: Gold OA and Green OA. Gold OA articles are published in journals that make all their articles freely available on the Internet, and all other OA articles are placed in the Green OA category. The study finds that all three indexes can indicate Gold OA availability in one way or another, but they differ dramatically when indicating Green OA availability: Google Scholar can offer free full-text indicators for 96 percent of Green OA articles, PubMed's rate is 29 percent, and Scopus's is zero. Subscription-based journal indexes and OpenURL link resolvers are, at present, incapable of indicating Green OA full-text availability. Vendors of subscription-based indexes and OpenURL link resolvers must overcome this challenge in order to stay relevant in the age of OA. In the meantime, librarians may want to take advantage of Google Scholar and PubMed to better serve library patrons.