Just want to issue a word of warning. This book is a "remake" of another Wayne Gould Su Doku book entitled "New York Post Fiendish Su Doku." As I'm almost done with the NY Post edition, I went searching for another Fiendish-type book. This edition caught my eye. When I received it and compared it to the NY Post book, I see that the puzzles are identical -- they are even ordered and numbered identically! I'm quite disappointed and dismayed that Harper Collins Publishers would publish identical books under differing names and covers.