[ “Definitely amazing fun for hours.”— Karina] [“Great puzzle book. I think anyone who enjoys Sudoku would like this collection.” — Ann] [“Perfect for the senior set!” — Sunny] [ “These ARE hard puzzles—humbling to one who’s been getting through other books rated “challenging” fairly quickly…great quality and fine to work on at home. ”— Carla] [ “Great level of difficulty: I love that pages are if good quality and white so that you can erase clearly snd that all puzzles are of the same level of difficulty.” — DMyers] [ “Stimulates my brain.” — Kindle Customer] [ “As advertised, the puzzles are hard!” — Daniel] [“Excellent” — Sandy] [“Fun and challenging: Challenging enough for an adult” — Carla] [“Difficult but as expected” — Monk] [ “Great for elderly dad” — Renee]