LaTeX Information
M. Downes: Short Math Guide for LaTeX (17 page PDF file)
Linked under the heading "Additional Documentation" on the AMS-LaTeX page.
T. Oetiker: The not so Short Introduction to LaTex (147 page PDF file) (PDF - 2.1 MB)
Writing Information
Academic Integrity at MIT: A Handbook for Students (PDF)
The Guide on General Scientific Writing (PDF)