Extreme Sudoku Puzzles – Volume 3

Extreme Sudoku Puzzles – Volume 2

Extreme Sudoku Puzzles – Volume 1

Very Hard Sudoku Puzzles – Volume 3

Very Hard Sudoku Puzzles – Volume 2

Very Hard Sudoku Puzzles – Volume 1

Hard Sudoku Puzzles – Volume 3

Hard Sudoku Puzzles – Volume 2

Hard Sudoku Puzzles – Volume 1

Medium Sudoku Puzzles – Volume 3