https://play.google.com/store/apps/details?id=com.mallusofts.sudokuchallenge&hl=en
Sudoku Challenge Offline - Apps on Google Play
Offline classic Sudoku in challenge mode with no advertisements
sudoku challengeoffline appson googleplay
https://www.lulu.com/shop/renerene/sudoku-challenge-brain-teasing-for-puzzle-enthusiasts/paperback/product-74gy9r.html
Sudoku Challenge: Brain-Teasing for Puzzle Enthusiasts
Get ready for an exciting Sudoku challenge, a captivating book filled with brain-teasing puzzles that will put your logical skills to the test. Immerse...
sudoku challengebrainteasingpuzzleenthusiasts