n, David. The Codebreakers. New York: Simon & Schuster, 1967. Lucas, Edward. The Snowden Operation. Seattle: Amazon Digital Services, 2015. Morell, Michael J. The Great War of Our Time. New York: Twelve, 2015. Sebag-Montefiore, Hugh. Enigma: The Battle for the Code. New York: John Wiley and Sons, 2001. Shils, Edward. The Torment o