136 books • 8 series
Sudoku Puzzle Book 400 Giant Size Puzzles, 200 MEDIUM and 200 HARD (Sudoku Puzzle Books, #34)
Sudoku Puzzle Book 200 Giant Size Puzzles, 100 HARD and 100 EXTRA HARD (Sudoku Puzzle Books, #32)
Sudoku Puzzle Book 200 Giant Size Puzzles, 100 MEDIUM and 100 HARD (Sudoku Puzzle Books, #31)
Sudoku Puzzle Book 200 EXTRA HARD Giant Size Puzzles (Sudoku Puzzle Books, #25) (Sudoku Puzzle Books Champion, #51)