36 books • 3 series
7700 IQ Puzzles in Multiple Formats to Get your Brain ready for any Intelligence Test (Career Growth, #15)
5300 IQ Puzzles to Make you More Intelligent and Help your Brain process Ideas and Concepts Faster (Career Growth, #12)
7000 IQ Puzzle Drills To Improve your Verbal and Lateral Thinking and Mathematical Skills to Ace Any Intelligence Test (IQ Test Prep Season 2, #8)
7000 IQ Puzzle Arithmetic Drills Involving Common Problem Types in Intelligence Tests Worldwide