- Sudoku 1,000 Medium Puzzles: Keep Your Brain Active for Hours. an Active Brain Series 2 Book
- Sudoku 400 Giant Size Puzzles, 200 Medium and 200 Hard, to Keep Your Brain Active for Hours: Take Your Playing to the Next Level with Two Difficulties in One Book
- Sudoku 1,500 Medium Puzzles: Keep Your Brain Active For Hours. An Active Brain Series 2 Book
- Sudoku 400 Giant Size Puzzles, 200 Easy and 200 Medium, to Keep Your Brain Active for Hours: Take Your Playing to the Next Level with Two Difficulties in One Book
- 500 Extra Hard Sudoku Puzzles: Active Brain Series Book 4





























