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"Encryption." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Encryption
"Heiroglyphics." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Heiroglyphics
"PGP." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/PGP
"Enigma Machine." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Enigma_machine
"Scytale." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Scytale
"Atbash Cipher." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Atbash_cipher
"Frequency Analysis." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Frequency_analysis
"Polyalphabetic Cipher." Wikipedia Project. 2005. http://en.wikipedia.org/wiki/Polyalphabetic_cipher
Weber, Glen B. "Veteran's History Project." The Veteran's History Project. 2005. The Library of Congress. http://lcweb2.loc.gov/cocoon/vhp/story/loc.natlib.afc2001001.02442/#vhp:clip
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