books.google.ch - The magnificent, unrivaled history of codes and ciphers -- how they're made, how they're broken, and the many and fascinating roles they've played since the dawn of civilization in war, business, diplomacy, and espionage -- updated with a new chapter on computer cryptography and the Ultra secret.Man...http://books.google.ch/books/about/The_Codebreakers.html?hl=de&id=SEH_rHkgaogC&q=substitution&utm_source=gb-gplus-shareThe Codebreakers
