Hard Sudoku puzzle books vol. 1: Hard, Very Hard and Extremely Hard Sudoku - Total 300 Sudoku puzzles to solve - Includes solutions
1000+ Sudoku Puzzles for Adults: A Book With More Than 1000 Sudoku Puzzles from Easy to Hard for adults.
Independently published
Loftus Sudoku Puzzle Cube - A Fun Portable Take On The Classic Sudoku Game - Can You Solve All 6 Sides, Multicolor
Funtime Gifts
BIG Sudoku Puzzles Book for Adults (Eye-Friendly Extra Large Print): Easy to Hard Book for Seniors & Teens With Solution