Killer Sudoku - Sudopedia

Killer Sudoku by Sudoku.com - Apps on Google Play

Extreme difficulty (maybe unsolvable?) killer sudoku : r/sudoku

Duncan's Killer SuDoku Solver

The Rule of 45 of Killer Sudoku (innies and outies)

Puzzle#102: Killer Sudoku 6x6

Ah! 111 Amazing Killer Sudoku Puzzles Volume 1: A Remarkable Collection of Logic Games, with Instructions and Answers, from Easy to Extreme, to Boost

Killer Sudoku Puzzle (Fun With Sudoku #376)

Killer Sudoku Hard To Extreme Puzzles - By Senor Sudoku (paperback) : Target

1,000 + New sudoku killer 10x10: Logic puzzles easy levels (Paperback)

Killer sudoku and Kin-kon-kan hard levels.: Puzzles Sudoku is a book of challenging levels. (Paperback)