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