Title: Beyond Extreme Sudoku Volume I: A collection of some of the toughest Sudoku puzzles known to man. (With their solutions.), Author: Antoine Alary
Title: Even More Extreme Sudoku: Even more of the toughest Sudoku puzzles known to man., Author: Antoine Alary
Title: More Extreme Sudoku: 200 more of the toughest Sudoku puzzles known to man. (With their solutions.), Author: Antoine Alary
Title: Beyond Extreme Sudoku Volume II: A collection of some of the toughest Sudoku puzzles known to man. (With their solutions.), Author: Antoine Alary
Title: Extreme Sudoku: A collection of 200 of the toughest Sudoku puzzles known to man. (With their solutions.), Author: Antoine Alary
Title: Beyond Extreme Sudoku Volume III: A collection of some of the toughest Sudoku puzzles known to man. (With their solutions.), Author: Antoine Alary