Below is a list of most important databases for your subject area. Relevant databases for Mathematics are listed here
Academic Search Complete is a scholarly, multi-disciplinary full-text database. The database features PDF content dating back as far as 1887, with the majority of full text titles in searchable PDF format.
The ACM DL is a vast collection of citations and full text from ACM journal, newsletter articles and conference proceedings.
JSTOR provides a comprehensive digital archive of important scholarly journals. It offers multidisciplinary and discipline-specific collections that include complete runs of journals as well as select monographs, transactions, and conference proceedings.
Scopus is the largest abstract and citation database of peer-reviewed literature, scientific journals, books and conference proceedings. Across all research fields - science, mathematics, engineering, technology, health and medicine, social sciences, and arts and humanities — Scopus delivers the broadest overview of global, interdisciplinary scientific information.