 The character "Nola Kaye" is an anagrammed form of "Elonka".In 2006, Dunin compiled a book of several hundred exercises in classical cryptography, which was published in the United States as "The Mammoth Book of Secret Codes and Cryptograms", and in the UK as "The Mammoth Book of Secret Code Puzzles".The book also includes a few details about several unsolved codes, such as "Kryptos".