http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
history of codes and ciphers in the United States prior to World War I
Historical background of the Signal Security Agency, vol. 1
159 pages : facsimiles, illustrations ; 28 cm.
"This book ... is essentially volume 1 of Historical background of the Signal Security Agency, written in 1946 by the Historical Section of the Army Security Agency."
Includes bibliographical references and index.