United States. Army Security Agency. Historical Section & Barker, W. G. (1978). The history of codes and ciphers in the United States prior to World War I. Aegean Park Press.
Chicago Style (17th ed.) CitationUnited States. Army Security Agency. Historical Section and Wayne G. Barker. The History of Codes and Ciphers in the United States Prior to World War I. Laguna Hills, Calif.: Aegean Park Press, 1978.
MLA (9th ed.) CitationUnited States. Army Security Agency. Historical Section and Wayne G. Barker. The History of Codes and Ciphers in the United States Prior to World War I. Aegean Park Press, 1978.
Warning: These citations may not always be 100% accurate.