Gardner, M. (1997). Penrose tiles to trapdoor ciphers: --and the return of Dr. Matrix (Rev. ed.). Mathematical Association of America.
Chicago Style (17th ed.) CitationGardner, Martin. Penrose Tiles to Trapdoor Ciphers: --and the Return of Dr. Matrix. Rev. ed. Washington, D.C.: Mathematical Association of America, 1997.
MLA (8th ed.) CitationGardner, Martin. Penrose Tiles to Trapdoor Ciphers: --and the Return of Dr. Matrix. Rev. ed. Mathematical Association of America, 1997.
Warning: These citations may not always be 100% accurate.