Why do you need books when you have google? I built my own without buying any books. The key thing to remember is that it's not cheaper to build one than it is to buy one outright, so I hope you're not expecting that.
A reasonably high-quality rifle that you build yourself will cost you upwards of $1200, and if you ever go to sell it, you'll never be able to recoup the costs.
You should also lookup what kind of tools you're going to need, which varies depending on how your rifle is configured.
There are a couple of decent AR15-oriented forums on the net. They will answer ANY question you might have. Before asking a question, though, learn how to use the site's search functionality. Chances are VERY good that someone else has already asked the very question you have.