MathSciNet - is the primary search tool for finding articles, conference proceedings, reviews, and journal articles in the field of mathematics.
Web of Science - covers highly used and highly cited scholarly materials in science back to 1908. Web of Science also indexes the social science and arts and humanities, making it a great tool for finding scholarly materials across multiple diciplines.
Google Scholar -is Google's searching across scholarly journals and books, and is great for searching across multiple disciplines.
Academic Search - is Microsoft's answer to Google Scholar.
Directory of Open Access Journals: Mathematics - The aim of the Directory of Open Access Journals is to increase the visibility and ease of use of open access scientific and scholarly journals thereby promoting their increased usage and impact. DOAJ journals are high quality, yet freely available.Check for their peer-review status on a case-by-case basis.
arXiv is a great resource for up-to-the-minute articles (pre-prints) across the sciences. Note that these articles are moderated, but not peer-reviewed (yet)
Getting BibTex citations out of MathSciNet:
Getting BibTex citations out of Web of Science:
Getting BibTex citations out of Google Scholar: