This sordid covert odyssey offers an inside look at how a pro works, throwing open a Pandora's box of bugs, mics, phone taps and more. The most comprehensive book ever on audio surveillance, it contains everything you ever wanted to know about the underground business of bugging. For academic study only.
This book cost $50, but the price is worth it as a reference for novelists. Hobbyists can find the schematics cheaper at RadioShack. I have a background in electronics, and the book is technically accurate. The author is witty which made the book a fun read. Unfortunately, someone stole my copy.