TY  - GEN
AU  - Singh,Simon
TI  - The code book: the secret history of codes and codebreaking : the secret history of codes and codebreaking 
SN  - 1-85702-889-9
U1  - 652.8 
PY  - 2000///
CY  - London
PB  - Fourth estate
KW  - Cryptography
KW  - History
ER  -