Times Big Book of Ultimate Killer Su Doku. 360 of the Deadliest Su Doku Puzzles, Paperback/The Times Mind Games

Challenge yourself at home with number puzzles If you like to live dangerously and push beyond your mental comfort zone, steel yourself for The Times' toughest Ultimate Killer puzzles. A bumper collection of more than 360 puzzles for hard-core solvers. Selected from the pages of The Times these puzzles will challenge the sharpest minds.