33 books
Sudoku Variations Vol2 200 Kropki Sudoku
Sudoku Variations Vol3 200 Easy Regions Sudoku
Sudoku Variations Vol4 200 Hard Regions Sudoku
Sudoku Variations Vol1 200 BUTTERFLY SUDOKU
200 Regions Sudoku Easy to Very Hard
200 Word and Number Logic Puzzles
400 Sudoku in Sohei Grids Vol1
400 Sudoku in Sohei Grids Vol2
200 Sudoku For Beginners