Gardner, Martin <br/><br/>
Penrose tiles to trapdoor ciphers : --and the return of Dr. Matrix 
Martin Gardner 
 - Rev. ed 
 - Wsshington, DC  Mathematical Association of America  c1997 
 - ix, 319 p. : ill. (some col.) ; 24 cm 
<br/><br/> Includes bibliographical references and index 
<br/><br/><label>ISBN: </label>9780883855218 
<br/><br/><label>ISSN: </label>97070505 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mathematical recreations
<br/><br/><label>Dewey Class. No.: </label>793.73 GAR