CitSeerX"CiteSeerx is an evolving scientific literature digital library and search engine that has focused primarily on the literature in computer and information science."
MIT D-Space"DSpace@MIT is a growing collection of MIT’s research that includes peer-reviewed articles, technical reports, working papers, theses, and more. "
Science.gov"Science.gov searches over 60 databases and over 2,200 scientific websites to provide users with access to more than 200 million pages of authoritative federal science information including research and development results."
Springer OpenOpen access full text publications from all areas of science, technology, medicine, the humanities and social sciences.
U.S. Department of Energy Citations DatabaseCitations to documents from the Department of Energy and the agencies preceded it, the Energy Research and Development Administration (ERDA) and the Atomic Energy Commission (AEC).