MathSciNet provides comprehensive coverage of pure and applied mathematics. It covers journal articles, books, and conference proceedings back to 1940.
Started in 1991, arXiv is an e-print repository and distribution server for research articles in physics, mathematics, statistics, computer science, nonlinear sciences, and quantitative biology. arXiv is open access and operated by Cornell University Library.
The Jahrbuch Project complements MathSciNet. It is based on Jahrbuch über die Fortschritte der Mathematic, and serves as an index to important mathematical publications for the time period of 1868 - 1942.
Issued annually by the American Statistical Association and the Institute for Mathematical Statistics, it is a comprehensive index to journal articles and monographs for mathematical statistics from 1974 forward.
INSPEC is the world's largest bibliographic database in the field of physics, electrical engineering and electronics, computers and control engineering, and information technology.