Ever consider joining an area C&S Society , or attend an annual C&S society sales and show ?
Visit a botanical center and visit the library ? You can read the reference books / book while there not sure about any check out and return policies they may have, usually they don't permit check outs of harder to find and rare books
Last resort is:
http://www.amazon.com/Cacti-Succulents-Illustrated-Encyclopedia-Anderson/dp/0754800288/ref=sr_1_16?s=books&ie=UTF8&qid=1364749852&sr=1-16&keywords=cactus+and+succulents+books

The ideal is as direct from Timberland Press as one can get for best prices by group ordering and bulk orders.

Greg Starr has just written a good book "Agaves: living sculptures for landscapes and containers". I like this book.I also Like Mary and Gary Irish's " Agave yuccas and related Plants and Howard scot Gentry's "Agaves of North America. These two are considered the classics on agaves.

Thanks both of you. I had already checked on C & S Society. None in my state. I would like to attend a sale and show if anyone knows of one close to Birmingham, Al. I am going to our main library. The one near me was totaled in our last storm. I hope I can find some titles that I want. I will be going to our local Books a Million to see if they can order the books you recommended.

There's a recently released fairly definitive guide on Aloes...called (surprise!) Aloes: The Definitive Guide
by S. Carter, L. E. Newton, J. J. Lavranos, C. C. Walker with something over 500 species described. Very expensive, but comprehensive.

The Aloes of South Africa book is very good, though of course less species.

If you have a public university nearby, you might browse their library, or see what you can get at your local library via inter-library loan, if cost is an issue.