Also, a Colpitts oscillator is a very vigorous oscillator. It may well continue oscillating even with a transistor clamp across the LC tank. And a parallel clamp transistor will degrade the 'Q' of the tank and increase the oscillator jitter. The answer is amazingly simple and elegant. I will post it when I have some time to convert the documentation to html.
Every engineer has a well-stocked reference library.
However, books are heavy when you have to move, the covers fall off, and coffee spills can make the pages hard to read. The web is a wonderful source of information. You can store a lot of files on your hard disk, and a good search program can make them easy to find. Here are a few good links. Transistor Theory HP Microwave and RF Application Notes has a wealth of information, including a section on bipolar transistor theory.