10 books • 4 series
Brain Games Sudoku (Everyday Crunch Your Brain, #1)
Sudoku Books For Adults (Very Hard 365 Days, #1)
Sudoku 400+ Puzzles (Sudoku 400, #1)
Sudoku Puzzle Books
Sudoku 365 Days
365 Puzzles Mensa Sudoku
Sudoku Hard To Extreme 2018 (Sudoku Puzzle Books Hard, #1)
Sudoku Activites Book 400 Puzzles
Sudoku Game for Kids
Sudoku Puzzle Books 400 Puzzles