Amazon
Hard Sudoku: 200+ Challenging Puzzles with Solutions | Volume 2 | Travel-Sized 6x9 Format | 2 Puzzles Per Page | Tough Brain Games for Adults and Seniors
Hard Sudoku: 200+ Challenging Puzzles with Solutions | Volume 2 | Travel-Sized 6x9 Format | 2 Puzzles Per Page | Tough Brain Games for Adults and Seniors