76 books • 2 series
Book #3: Sudoku Book 1,000 Hard Puzzles
Book #4: Sudoku Book 1,000 Extra Hard Puzzles
Book #6: Sudoku Book 1,000 Puzzles, 500 Medium and 500 Hard
Book #7: Sudoku Book 1,000 Puzzles, 500 Hard and 500 Extra Hard
Book #8: Sudoku Book 500 Easy Puzzles
Book #44: Sudoku Book 1,600 Puzzles, 400 Easy, 400 Medium, 400 Hard and 400 Extra Hard
Book #46: Sudoku Book 1,600 Puzzles, 800 Medium and 800 Hard
Book #47: Sudoku Book 1,600 Puzzles, 800 Hard and 800 Extra Hard
Book #49: Sudoku Book 200 Medium GIANT Size Puzzles
Book #50: Sudoku Book 200 Hard GIANT Size Puzzles