Extreme Sudoku Book Four: 100 Hard To Solve 25 x 25 Sudoku Puzzles With Solutions in Bloomington, MN

100 very hard 25 number Sudoku puzzles. One puzzle on a page Using a 25 x 25 square grid. These puzzles are for expert Sudoku players. The solutions are in the back of the book.
This is a Sudoku book for adults.