Will Shortz Presents Ferocious Sudoku: 200 Hard Puzzles

Will Shortz Presents Tame Sudoku: 200 Easy Puzzles

Will Shortz Presents Wild Sudoku

Will Shortz Presents Surrender to Sudoku: 200 Irresistibly Hard Puzzles

Will Shortz Presents Survival of the Fittest Sudoku: 200 Hard Puzzles

Will Shortz Presents The Huge Book of Hard Sudoku: 300 Challenging Puzzles

Will Shortz Presents Mind-Melting Sudoku: 200 Cranium-Crushing Puzzles

Will Shortz Presents Extra Hot Sudoku: 200 Hard Puzzles: Hard Sudoku Volume 1

Beyond Black Belt Sudoku: If you have to ask, it's too hard for you. (Martial Arts Puzzles Series)

Sudoku 3: 200 Puzzles: Hard to Extreme

Will Shortz Presents Sweater Weather Sudoku: 200 Challenging Puzzles: Hard Sudoku Volume 2

Will Shortz Presents Hard Sudoku Volume 1: 200 Challenging Puzzles

Will Shortz Presents The Little Orange Book of Harrowing Sudoku: 335 Frighteningly Fierce Puzzles