His books include the definitive history of cryptography, "The Codebreakers" (1967, revised 1996, Scribner's, ISBN 0684831309 ); also "Seizing the Enigma" and "Hitler's Spies".
(book) "The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth of American Codebreaking". New Haven, CT: Yale University Press, 2004. ISBN 0300098464