Copeland, B. Jack. Colossus: The Secrets of Bletchley Park’s Codebreaking Computers. New York: Oxford, 2006.
Hungerford, Thomas W. Abstract Algebra: An Introduction. U.S.: Thomson Learning, 1997.
Loepp, Susan, and William K. Wooters. Protecting Information: From Classical Error Correction to Quantum Cryptography. New York: Cambridge University Press, 2006.
Ratcliff, Rebecca Ann. Delusions of Intelligence. New York: Cambridge University Press, 2006.