Sudoku Puzzle Book: Sudoku Activity Book with 100 Puzzles for Adults, Hard LevelThis is the perfect book to buy for yourself. It will help you:Keep your mind sharp with challenging puzzlesPass the time while waiting at the doctor's office, DMV, or airportProvide hours of entertainment especially on weekends and rainy daysMake road trips or subway commutes fly byIt also makes an excellent gift. Family members, friends, and coworkers will love to receive this. Anyone who loves Sudoku, puzzles or a new challenge will love this book!