Not exactly sure if this is what you're looking for, but I used
this book for reference for a couple of essays and it's pretty comprehensive for the
study of rhetoric. Pricey, but very likely to be in your university library.
If you're just looking for canonical examples of rhetoric with a bit of discussion/analysis, you could maybe have a look at The Norton Reader - Non-Fiction.
Having written all of that, it has just occurred to me that you're probably looking for something more to do with
using rhetoric, rather than learning about past examples. Those books should be interesting background reading though. Sorry I can't help more - always been a reader rather than a writer.
