Very Hard Sudoku Puzzles Volume 1: Very Hard Sudoku Puzzles For Advanced Players: Cross, Simon: 9781541242432: Amazon.com: Books
Sudoku Book 800 Puzzles, 400 Medium and 400 Hard: Sudoku Puzzle Book With Two Levels of Difficulty To Improve Your Game (Sudoku Book Series): Book, Sudoku: 9781544185729: Amazon.com: Books
Hard Sudoku Puzzle Book Volume 2: Hard Sudoku Puzzles For Advanced Players: Forkes, Brad: 9781542916424: Amazon.com: Books
Sudoku 15x15 Puzzle Grandi - Da Facile a Diabolico - Volume 27 - 276 Puzzle (Italian Edition): Snels, Nick: 9781512071818: Amazon.com: Books
Sudoku Book 1,600 Puzzles, 800 Hard and 800 Extra Hard: Bargain Size Sudoku Puzzle Book With Two Levels of Difficulty To Improve Your Game (Sudoku Book Challenger Series): Book, Sudoku: 9781546743576: Amazon.com: Books
Danny's Extreme Sudoku Large Print: 100 Hard Sudoku Puzzles ? 1 Per Page: Danny: 9781543261301: Amazon.com: Books