1. Basics/ Introduction : Digital Communication Techniques by Taub and Schilings.
2. Spread Sprectrum Textbooks for detailed study (please check out ebook forum for these books there are around 10 books dealing with the topic ) .
Adaptive can mean a lot of stuff, but the simplest thing that comes to mind is for a frequency hopped system with 25 frequency channels, if 2 of the channels are interferred with, the algorithm just starts skipping those 2 frequencies for a while. Solves CW tone interferrors and dispersive fade "suck outs".