- David Karn Sudoku - Medium to Hard Vol 2: 100 Puzzles, Extra Large Print, 42 pt font size, 1 puzzle per page
- David Karn Sudoku - Medium to Hard Vol 1: 100 Puzzles, Extra Large Print, 42 pt font size, 1 puzzle per page
- David Karn Sudoku - Medium to Very Hard Vol 1: 168 Puzzles, Travel Size, Regular Print, 24 pt font size, 2 puzzles per page
- David Karn Sudoku - Very Hard to Extreme Vol 1: 120 Puzzles, Large Print, 36 pt font size, 1 puzzle per page
- David Karn Sudoku - Very Hard to Extreme Vol 2: 100 Puzzles, Extra Large Print, 42 pt font size, 1 puzzle per page