arXiv is a repository of electronic preprints, or e-prints, in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, and statistics.
Social Science Research Network (SSRN) is an open access repository of abstracts and full text papers by social science researchers from across the world.
PubMed is a free resource thatincludes over 24 million citations for biomedical literature from MEDLINE, life science journals, and online books. Coverage includes the fields of biomedicine and health, portions of the life sciences, behavioral sciences, chemical sciences, and bioengineering.
The Digital Public Library of America brings together the riches of America’s libraries, archives, and museums, and makes them freely available to the world.
HathiTrust is a partnership of academic and research institutions, offering a collection of millions of titles digitized from libraries around the world.
