Handy paperback with 600 Sudoku puzzles with solutions and instructions.
Green Edition version = medium puzzles (there are easy, medium, difficult, and very difficult)
Puzzle where you want! On the train, on the bus, in the waiting room, or at home.
The paperback format makes your Sudoku paperback a companion. You will not be bored.
In addition to having fun, you also train your brain.