01141cam a2200289 4500 60921092 TxGeo 20100311120000.0 081112s2009||||||||||||||||||||||||eng|u 2008048970 9780525479604 hc 0525479600 hc (OCoLC)272665437 DLC DLC TnLvILS TxGeo Blackwood, Gary L. Mysterious messages : a history of codes and ciphers / Gary Blackwood ; designed and illustrated by Jason Henry. 1st ed. New York : Dutton Children's Books, 2009. 170 p. : ill. ; 21 cm. Includes bibliographical and web references (p. 166) and index. Examines history's most dangerous secrets and ciphers, and shows young spies how to use them for themselves. 20100311. Cryptography History. Ciphers History. Henry, Jason. QS5