Sudoku for Kids: Unicorn Puzzles for Kids : Sudoku 4x4, 5x5, 6x6, 7x7, 8x8, 9x9 Grids From Beginner to Advanced- Gradually Introduce Children to Sudoku and Grow Logic Skills! (Series #1) (Paperback) -
5x5!? Easy SUDOKU Eccentric Version by Kozo Terai
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Sudoku for Kids — Free Printable Sudoku Puzzles for Kids