556 books • 56 series
Book #3: Kropki Sudoku Puzzles - 200 vol. 3
Book #4: Kropki Sudoku Puzzles - 200 vol. 4
Book #1: Numbricks Puzzles - Easy 200 vol. 1
Book #3: Numbricks Puzzles - Hard 200 vol. 3
Book #1: Samurai Sudoku - Easy 200 vol. 1
Book #2: Samurai Sudoku - Medium 200 vol. 2