The "Colorado" code.
Publisher: General Headquarters, American Expeditionary Forces
Published: 1918
Place of publication: S.l.
Language: eng
Number of pages: 52
Subjects: Ciphers -- Handbooks, manuals, etc.  Cryptography -- United States.  World War, 1914-1918 -- Cryptography.
Description: 47 p. ; 20 cm.