Anon. “Cryptography” in Encyclopaedia Britannica, Vol. 6, 14th edition, New York and London, 1929. (Contains a bibliography.)
Ball, W. W. Rouse. “Cryptographs and Ciphers” in his Mathematical Recreations and Essays. 7th edition, 1917 and later. (Latest edition is the 11th, 1939.)
Blair, William. “Cipher in Diplomatic Affairs” in Rees’s Cyclopaedia. 1803-1819.
Candela, Rosario. The Military Cipher of Commandant Bazeries, An Essay in Decrypting. New York, 1938.
Friedman, William F. (Lt.-Colonel). “Codes and Ciphers” in Encyclopaedia Britannica, Vol. 5, 14th edition, New York and London, 1929. (Contains bibliography.)
—. “Edgar Allan Poe, Cryptographer” in American Literature, A Journal of Literary History, Criticism and Bibliography, Vol. 8, No. 3, Nov. 1936, pp. 266-280. Duke University, Durham, N. C.
Hulme, Frederick Edward. Cryptography, or, The History, Principles and Practice of Cipher-Writing. London, 1898.
Lange, André and E. A. Soudart. Traité de Cryptographie. Paris, 1st edition, 1925, new edition, 1935. (Contains an extensive bibliography.)
Lange, André. Cryptography. Translated from the French by J. C. H. Macbeth, London and New York, 1922.
Pratt, Fletcher. Secret and Urgent, The Story of Codes and Ciphers. Indianapolis, 1939.