Sudoku Puzzle Book, 600 Puzzles, 300 MEDIUM and 300 HARD: Improve Your Game With This Two Level Book (Sudoku Puzzle Books Champion Series)

Sudoku: Medium - Hard: 200 advanced sudoku puzzles

Funster 1,000+ Sudoku Puzzles Easy to Hard: Sudoku puzzle book for adults

Funster Tons of Sudoku 1,000+ Easy to Hard Puzzles: A bargain bonanza for Sudoku lovers

Hard Sudoku puzzle books vol. 1: Hard, Very Hard and Extremely Hard Sudoku - Total 300 Sudoku puzzles to solve - Includes solutions (Hard to extreme)

512 SUDOKU Puzzles: Easy, Medium, Hard and Extreme Sudoku Puzzle Book including Instructions and answer keys

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

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

Big Book of Sudoku - Medium to Hard - 1000 Puzzles: Huge Bargain Collection of 1000 Puzzles and Solutions, Medium to Hard Level, Tons of Challenge for your Brain!

Will Shortz Presents Hard Sudoku Volume 2: 200 Challenging Puzzles