Penrose tiles to trapdoor ciphers :
Gardner, Martin,
Penrose tiles to trapdoor ciphers : --and the return of Dr. Matrix / Martin Gardner. - Rev. ed. - Washington, D.C. : Mathematical Association of America, c1997. - ix, 319 p. : ill. (some col.) ;
0883855216 (pbk.)
Mathematical recreations
51-8 / GAR
Penrose tiles to trapdoor ciphers : --and the return of Dr. Matrix / Martin Gardner. - Rev. ed. - Washington, D.C. : Mathematical Association of America, c1997. - ix, 319 p. : ill. (some col.) ;
0883855216 (pbk.)
Mathematical recreations
51-8 / GAR