Thomas, Paul B. Secret Messages. New York and London, 1928. 2nd printing, 1929.
Windolph, J. Fred (“Phil Down”). “Cryptograms: Their Construction and Solution” in A Key to Puzzledom, pp. 53-64. New York, 1906. (Simple substitution ciphers only.)
Yardley, Herbert Osborne (Major). Yardleygrams. Indianapolis, 1932. (The London edition (1932) bears the title Ciphergrams.)
Advanced Works
Friedman, William F. (Lt.-Colonel). Elements of Cryptanalysis. Washington, Gov. Printing Office, 1924. “For Offcial Use Only.” (Contains a bibliography. Out of print and unobtainable.)
—. See also Riverbank Publications.
Givierge, Marcel (General). Cours de Cryptographie. Paris, 1st edition, 1925, 2nd edition, 1932.
Hitt, Parker (Colonel). Manual for the Solution of Military Ciphers. Fort Leavenworth, Kans., 1st edition, 1916, 2nd edition, 1918.
Riverbank Publications. Papers (except No. 19) by W. F. Friedman. Department of Ciphers, Riverbank Laboratories, Geneva, Illinois.
No. 15, 1917. “A Method of Reconstructing the Primary Alphabet.”