hi, i bought a book called SUDOKU MANIA that apparently was created by THE SUDOKU INSTITUTE. it has seven levels of play from white belt to black belt. i am currently on purple belt and i am finding the puzzles a cinch to solve!!! i'm not very good at sudoku, but these puzzles are taking me between two and six minutes to solve. and before each new section there's a blurb about the new challenges you'll face, but all the puzzles look the same and have about forty boxes filled in for you. the black belt section features very large puzzles with numbers AND letters. has anyone ever used this book? i found it in a grocery store for 6 bucks. are the DELL or PUZZLER books recommended for serious players?
i think i should stick with the WHITE BELT SUDOKU book for now b/c those puzzles are pretty tough.
i would appreciate recommendations for other sudoku books that will challenge me and help me improve my puzzle solving. thank you.