David Kahn 
How I Discovered World War II”s Greatest Spy and Other Stories of Intelligence and Code [EPUB ebook] 

This book recounts the desperate efforts to gather information during World War II and the Cold War. The author provides insight into the dark realm of intelligence and code that will fascinate cryptographers, intelligence personnel, and the millions of people interested in military history, espionage adventure, and world affairs. David Kahn is universally regarded as the dean of intelligence historians. Authoritative and addictively readable, this book, by revealing the past, helps guide present and future intelligence efforts.