Sudoku 20x20 Volume 1: Sudoku Xtra Specials
Dr Gareth Moore is the author of a wide range of brain-training and puzzle books for both children and adults, including The Mammoth Book of Fun Brain Training, The Rough Guide Book of Brain Training, Keep Your Brain Fit: 101 Ways to Tone your Mind, and The Mammoth Book of Brain Workouts. He also writes the monthly magazine Sudoku Xtra and runs the puzzle website www.puzzlemix.com.