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Himmelstein DS, Romero AR, Levernier JG, Munro TA, McLaughlin SR, Greshake Tzovaras B, Greene CS.2018. Sci-Hub provides access to nearly all scholarly literature. PeerJ Preprints6:e3100v3https://doi.org/10.7287/peerj.preprints.3100v3
The website Sci-Hub enables users to download PDF versions of scholarly articles, including many articles that are paywalled at their journal’s site. Sci-Hub has grown rapidly since its creation in 2011, but the extent of its coverage was unclear. Here we report that, as of March 2017, Sci-Hub’s database contains 68.9% of the 81.6 million scholarly articles registered with Crossref and 85.2% of articles published in toll access journals. We find that coverage varies by discipline and publisher and that Sci-Hub preferentially covers popular, paywalled content. For toll access articles, green open access via licit services is quite limited, while Sci-Hub provides greater coverage than a major research university. Our interactive browser at https://greenelab.github.io/scihub allows users to explore these findings in more detail. For the first time, nearly all scholarly literature is available gratis to anyone with an Internet connection, suggesting the toll access business model will become unsustainable.
Version 3 contains several major updates. Journal information was updated to the October 2017 release of Scopus, with additional patches to standardize publisher names, causing many coverage measures to change slightly. We compared Sci-Hub's coverage to the University of Pennsylvania Libraries. The Google Trends, Bitcoin donations, and Sci-Hub access logs analyses were extended through the end of 2017. Finally, we performed revisions in response to peer review at the journal eLife. This version includes a more comprehensive discussion of the subscription publishing model and how Sci-Hub could disrupt it.