Keep your temper in check when solving this book of hard to extreme Sudoku puzzles. You're likely to lose your patience when it takes a good few minutes for you to figure out the patterns in the puzzles. But once you figure it out, oh what joy You will feel a burst of energy, along with improved self-confidence and an undeniable happiness. Begin solving today. | These Make Me Very Happy Sudoku Hard to Extreme by Senor Senor Sudoku, Paperback | Indigo Chapters