A Primer of Mathematical Writing, Second Edition
This is a tract on the art and practice of mathematical writing. Not only does the book cover basic principles of grammar, syntax, and usage, but it takes into account developments of the last twenty years that have been inspired by the Internet. 
There is considerable discussion of TeX and other modern writing environments. We also consider electronic journals, print-on-demand books, Open Access Journals, preprint servers, and many other aspects of modern publishing life.