Original: In 2006, Dunin published a book of 600 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.
Simplified: In 2006, she wrote a book with hundreds of puzzles in it, called The Mammoth Book of Secret Codes and Cryptograms.