About the Author

The Diagram Group, founded in 1960, has been producing high-quality graphic and text content for more than 50 years. Specializing in detailed diagrams, charts, tables, maps, and illustrations and the text to support them, the Diagram Group's titles have sold over nine million copies in 53 languages and 48 countries. Keith Kay is the author of a variety of optical illusion and brainteaser books. His previous titles include: The Little Giant Book of Optical Illusions (9781402749711), The Little Giant Book of Optical Tricks, BrainStrains Great Color Optical Illusions, BrainStrains Eye-Popping Puzzles, and Colorful Puzzles for Wise Eyes.