Kahn, David. The Codebreakers. New York: Macmillan, 1967.

Laffin, John. Codes and Ciphers. New York: Abelard-Schuman, 1964.

Lunde, Donald Т., M.D. Murder and Madness. New York: W. W. Norton & Co., 1979.

Oken, Alan. As Above, So Below. New York.

Pratt, Fletcher. Secret and Urgent. New York.

Sest, Mann, Flangan, Cowen. The Phenomenon Book of Calendars. New York: Simon & Schuster, 1978.

Snyder, LeMoyne. Homicide Investigation. Springfield, Illinois: Charles C. Thomas Co., 1977.