APA (7th ed.) Citation

Clark, R. (1977). The man who broke purple: The life of the world's greatest cryptologist, Colonel William F. Friedman. Weidenfeld and Nicolson.

Chicago Style (17th ed.) Citation

Clark, Ronald. The Man Who Broke Purple: The Life of the World's Greatest Cryptologist, Colonel William F. Friedman. London: Weidenfeld and Nicolson, 1977.

MLA (9th ed.) Citation

Clark, Ronald. The Man Who Broke Purple: The Life of the World's Greatest Cryptologist, Colonel William F. Friedman. Weidenfeld and Nicolson, 1977.