1,000 + Collection sudoku killer 12x12: Logic puzzles easy levels (Paperback) | Boulder Book Store
Logic Wiz: Squares Sudoku. Jigsaw(irregular), Reflection, Arrow & Thermo Sudoku. Rules and links in the first comment. : r/sudoku
400 classic Killer sudoku 9 x 9 MEDIUM + BONUS 250 Hidoku puzzles: Sudoku with MEDIUM levels puzzles and a Hidoku 9 x 9 very hard levels by Basford Holmes, Paperback | Barnes & Noble®
1,000 + Collection sudoku killer 12x12: Logic puzzles easy - medium - hard - extreme levels (Paperback) | Viewpoint Books
Super-Tough Sudoku Puzzles, Book 12 - KrazyDad
Killer sudoku and Kin-kon-kan extreme levels.: Puzzles Sudoku very difficult levels. (Paperback) | Village Books: Building Community One Book at a Time