LEADER 00000nam 2200181 a 4500 001 071671986X 003 UkHlHU 007 t 008 991026s1989 000 020 071671986X 040 UkHlHU 100 1 Gardner, Martin,|d1914- 245 10 Penrose tiles to trapdoor ciphers. 260 |bWH Freeman,|c1989. 300 311p. 650 0 Mathematics|xPuzzles and Games. 936 UCS bib. record 946 260 lacks |a
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