676 books • 33 series
Sudoku Variants Puzzle Books Medium to Hard - Volume 1 (Sudoku Variants Puzzle Books Medium to Hard, #1)
Sudoku Variants Puzzle Books Medium - Volume 2 (Sudoku Variants Puzzle Books Medium, #2)
Sudoku Variants Puzzle Books Medium - Volume 1 (Sudoku Variants Puzzle Books Medium, #1)