TY  - BOOK
AU  - Gardner,Martin
TI  - Penrose tiles to trapdoor ciphers
SN  - 0716719878 (pbk.)
AV  - QA95 .G298 1989
PY  - 1989///
CY  - New York
PB  - Freeman
KW  - Mathematical recreations
N1  - Includes bibliographies and index
ER  -