Penguin Sudoku: 2009 by David J. Bodycombe
A Sudoku a day helps you work, rest and play. Welcome to the addictive puzzle that is seriously good for you. Here are 365 brand new sudokus, star-rated from novice level through difficult to utterly fearsome. These games will help your brainpower, your concentration and your deduction skills. With instructions and solutions included, all you need is a pencil to give your mind a daily workout.