Ludii Portal

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

Irregular Killer Sudoku — Knight Features

Killer sudoku (Question for experienced players) : r/sudoku

Interactive Killer Sudoku by KrazyDad

A Gorgeous Killer Sudoku Trick

Killer Samurai Sudoku

Read PuzzleLife Killer Sudoku magazine on Readly - the ultimate magazine subscription. 1000's of magazines in one app

Killer Sudoku Puzzle Book for Adults: 200 Hard to Very Hard Puzzles 9x9 (Volume2) (Paperback)

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

The Jumbo Book of Killer Sudoku — Intermediate to Hard - Puzzle Genius