Sudoku-Stak : 9781618971784 : 30 Jan 2012 : "I truly LOVE your puzzles. Thank you for a new and challenging twist on the sudoku puzzle. These are, by far, my favorite variation." - Jane, Bethesda, USA "This very interesting advancement to the puzzle has rekindled my family's interest in sudoku. It's just amazing that so many numbers can go together in only one way." - Peter, Banstead, UK "After finishing my first sudoku puzzle, I was hooked. Having them in 3-D form only makes me want to do them 3 times more! Thank you for cubing the complexity of the challenge." - Rory, Buderim, AUS About the Author: Richard John is the mastermind behind this uniquely challenging form of Sudoku that expands the 2-dimensional puzzle into a mind-bending cube of seemingly unsolvable numbers. His engineering background and perseverance helped create what you hold in your hands today. Richard runs a family business and teaches yoga. He lives with his wife, Claire, in Harare, Zimbabwe. Publisher's websi