There are about 8000 book titles on the subject of public speaking. I recommend that you not buy any of them without first borrowing some from your friendly local public library. (Here in Boise, Idaho we only have a couple hundred books on the subject.) No matter what level you are at, or what problem you wish to solve you probably can find a promising title (if not several). It’s similar to browsing for cookbooks.
There are books for those starting from complete ignorance of the topic like:
Laurie Rozakis, Complete Idiot’s Guide to Public Speaking or
Malcolm Kushner, Public Speaking for Dummies
Many college textbooks also are out there, but I have yet to see the truly honest title, Public Speaking for Naïve College Students
There are books that address fear, uncertainty, and doubt like:
Ivy Naistadt, Speak Without Fear or
Lilyan Wilder, 7 Steps to Fearless Speaking
There are many books of small numbers like:
Carmine Gallo, 10 Simple Secrets of the World’s Greatest Business Communicators or
Mark Wiskup, Presentation S.O.S.: From Perspiration to Persuasion in 9 Easy Steps
For marketing reasons there are never titles that admit that the small number of steps or "secrets" truly are neither simple nor easy.
There are many other books of large numbers (or smorgasbords) like:
Caryl Rae Krannich, 101 Secrets of Highly Effective Speakers or
Mandar Marathe, The Successful Speaker: 273 Tips for Powerful Presentations
Just browse through the contents to find your topic of interest.
Finally, there are advanced books like:
Timothy Koegel, The Exceptional Presenter or
Margaret Ryan, Extraordinary Oral Presentations