Sudoku: Medium to Hard Volume 1
Sudoku 3: 200 Puzzles: Hard to Extreme
Sudoku Vol. 2 Puzzle Pad: Easy to Medium
Sudoku: Easy to Medium
Sudoku (Ultimate Spiral Puzzles)
Sudoku 3: Extreme to Grand Master
mental_floss Sudoku: It's the Brain Candy You've Been Craving!
The Big Book Of Sudoku (500 Puzzles)
Will Shortz Presents The Huge Book of Hard Sudoku: 300 Challenging Puzzles
Brain GamesĀ® Sudoku (Brain Games (Unnumbered))