MathSciNet
Database of reviews, abstracts and bibliographic information for much of the mathematical sciences literature, from the American Mathematical Society (AMS).
Web of Science, Web of Science database
Interdisciplinary index that provides citations for high impact journals. Useful for forward citation searching. Includes some indexing and full-text linking for ProQuest Dissertations and Theses. Access note: To access the API, set up your account and select "Web of Science Starter API" at Step 3 “Subscribe to an API.” For research support using the API, please contact the Center for Research Data & Digital Scholarship.
arXiv.org
Online archive and distribution server for research articles and pre-prints.