Sudoku Book for Adults and Seniors with 3 Levels of Difficulty: 402 Puzzles & Solutions, Easy to Hard (The Perfect Gift for Puzzle Lovers) (Gifts for Men & Women) Publishing, Rody
Logic Grid Puzzles Triple Trouble: 150 Devilishly Fun Puzzles (3 Books in 1) (Logic Puzzles for Adults – Platinum Collection) Unicorn Books