MathSciNet is the on-line version of Mathematical Reviews and is very useful in identifying references related to a paper. Indexing is by author, title, keywords, classification numbers, and all words in reviews.
Current Index to Statistics is a bibliographic index to publications in statistics and related fields. Indexing is by title and keywords.
MR Lookup is a convenient tool for finding the exact reference for a particular paper.
MSC 2010 is the standard subject classification scheme used in the Annals and other major journals.
Standard Journal Title Abbreviations are provided by Mathematical Reviews.
MiKTeX is a free TeX program for Windows. It includes standard TeX and LaTeX, a dvi viewer, conversion software to produce postscript and pdf files.
Ghostview is a free postscript viewer available for most computer systems.
The Adobe Acrobat Reader is a free PDF viewer available for most computer systems.
Information on English style and grammar
Classic references for English usage can be found at the Great Books Online service of Bartleby.com. The references include the 1918 edition of The Elements of Style by William Strunk, Jr., the 1908 edition of The King’s English by H. W. Fowler, and the 1996 edition of the American Heritage® Book of English Usage.
The Guide to Grammar and Style by Jack Lynch is written for students in writing classes, but provides a lot of useful information and references for other sources.
THE ALT.USAGE.ENGLISH FAQ FILE includes interesting discussion of English usage. If you don’t like the recommendations of the other style guides, you can probably find support for your position here.