Bletchley Park museum
SOE, Special Operations Executive, by Bernie Harris.
Camp X
The Navajo Code Talkers
N.K.V.D. & K.G.B. Home Page
Tunnel and Shelter researching
Deadly Knowledge
National Cryptologic Museum
Enigma Cipher Machine
The Alan Turing Internet Scrapbook
Decoding Nazi Secrets
Codebreaking and Secret Weapons in World War II