Gilbert S. Vernam, "Cipher Printing Telegraph Systems For Secret Wire and Radio Telegraphic Communications", Journal of the IEEE, Vol 55, pp109-115 (1926). Gilbert S. Vernam, "Automatic Telegraph Switching System Plan 55-A", AIEE Transactions on Communication and Electronics, May 1958, p. 239. Also in Western Union Technical Review Vol 12 No 2, April 1958, p. 37. Gilbert S. Vernam, "Printing Telegraph Operation of Way Wires", AIEE Transactions vol 57, July 1938, p. 365. Gilbert S. Vernam, "An Automatic Concentration Unit for Printing Telegraph Circuits", Electrical Communication, April 1932, p. 200.