An extensive effort to explain the art of mathematical writing is
the book *Mathematical Writing* by Knuth, Larrabee, and
Roberts. The compressed plain TeX file of the text can be downloaded
here.
The book will be placed on reserve (if possible).

Another book on mathematical writing is *Writing Mathematics
Well* by Leonard Gillman. I haven't seen this, but it has received
good reviews.

For some examples of good undergraduate mathematics writing, see the Rose-Hulman Undergraduate Math Journal (click on "Downloads" or "Download Articles").

Here is some good general advice about giving math talks

by Curtis Bennett and Frank SottileThe internet is full of useful information on mathematical writing. A Google search on "mathematical writing" (in quotes) had over 13,000 hits, though I don't recommend reading all of them. Three nice sites are the following.

- Errors in mathematical writing by Keith Conrad (5 page pdf file)
- Phase Two guidelines, much of it relevant here.
- A Guide to Writing Mathematics by Kevin P. Lee (17 page pdf file).