Sudoku Collection: 200 Hard Windoku Sudoku Puzzles 9x9

200 excellent puzzles 9x9 at the level of Hard. Perfect for Advanced and Intermediate players. All riddles have only 1 solution. 2 puzzles per page.The font size is correct, you will not have to strain your eyes when solving puzzles. High quality paper and print (all puzzles read well, easy to write with pen and pencil without worry of bleed-through). Windoku is based on the original Sudoku grid, with the same rules and numbers-1 to 9. Contain additional four regions (shaded) 3 x 3(no number may appear twice in any row or column and rectangles of 3x3).