Samurai Sudoku Puzzle Books for Adults: Japanese Math Puzzle Logic Book | Easy to Hard | 90 Puzzles: Publishing, Puzzle King: 9798674899709: Amazon.com: Books
Amazon.com: Sudoku Puzzle Book for Adults, Young Adults and Teens: 1000 Sudoku Puzzles Easy to Hard including Standard Sudoku, Killer Sudoku, Sudoku Samurai, Marathon and more: 9798759732396: Publishing, BRIANTINKER: Books
1,000 + Mega sudoku killer 8x8: Logic puzzles hard levels (Killer sudoku): Holmes, Basford: 9781687526397: Amazon.com: Books