Ciphers
Spy Files: Codes and Ciphers
ByAdrian D. Gilbert
2008 • 32 pages
The Story of Codes
ByStephen Pincock,Mark Frary
2019 • 1 Reader • 192 pages
Hidden Secrets: The Complete History of Espionage and the Technology Used to Support It
ByDavid L. Owen
2002 • 1 Reader • 224 pages