Enkripcija — разлика између измена

* Robert A. Burgelman, Claiyton M. Christensen, Steven C. Wheelwright, Strategic management of technology and inovation, 4th Edition (2004, ppp. 398)

* Helen Fouché Gaines, “Cryptanalysis”, 1939, Dover. {{page|year=|id=ISBN 0-486-20097-3|pages=}}

* David Kahn,. ''The Codebreakers - The Story of Secret Writing'' (ISBN 0-684-83130-9). {{page|year=1967|id=|pages=}}

* Abraham Sinkov,. ''Elementary Cryptanalysis: A Mathematical Approach'', Mathematical Association of America,. {{page|year=1966|id=ISBN 0-88385-622-0|pages=}}