Mensa Killer Sudoku: More than 200 of the most difficult number puzzles

Mensa Sudoku: Put your logical reasoning to the test with more than...

The Guardian Cryptic Crosswords 2: A compendium of more than 100 difficult...

Mensa Logic Puzzles: More than 150 brainteasers to test your powers of deduction

Mensa's Most Difficult Number Puzzles: Prove your logical and numerical abilities against...