MathSciNet: Math and physics literature 1940-
Oxford Reference Online- Physical Sciences & Mathematics: Collection contains reference works covering Astronomy, Chemistry, Cosmology, Mathematics, Physics, Scientists, Space Exploration, Statistics, Weights, Measures, and Units.
Web of Science (Science Citation Index): Allows searching the journal literature in all branches of the sciences not only by subject or author, but also by cited author or article. 1955-