U.S. National Library of Medicine; affiliated with the National Institutes of Health (NIH). Covers medical and some life science journals. Compiles citations; some citation sources may need to be accessed from a UMaine account.
Provides access to a digital library containing journals, books, and primary sources in the sciences, social sciences, and humanities. Very recent articles may not be accessible, but this is one of the best databases to check for older materials. Requires login with UMaine account.