Sudoku: Small Travel Size Sudoku Puzzle Book | Pretty Pocket-Size Sudoku Puzzle Book for Adults | Perfect for Purse, Briefcase or Bag: ZaZa, Ameila: 9781691253463: Amazon.com: Books
Amazon.com: Pocket Sudoku - a compact & travel-friendly puzzle book: only 4 x 6 inches in size | 5 Difficulty Levels | easy - normal - hard - very hard - extreme