TY  - BOOK
AU  - Welsh, Dominic.
TI  - Codes and cryptography
SN  - 0198532873
U1  - 652.8 
PY  - 1988///
CY  - Oxford
PB  - Clarendon Press
KW  - Ciphers
KW  - Cryptography
N1  - Includes bibliographical references and index
ER  -