Preprint servers are useful for finding unpublished and accepted manuscript versions of scholarship uploaded by authors. Discovery of preprints is possible in Google Scholar, but also possible by following the preprint servers on Twitter or using the browser extension unpaywall.org. Below is a non-inclusive list of preprint servers.
Popular preprint servers:
For access to e-books, online journals, databases:
Find Open Access versions of paywalled articles with the Upaywall browser app.
Already know which article you need? Enter the citation in the Find Items by Citation form to access it.