SUDOKU - schwer bis sehr schwer 1

Ten full years lie between volume 1 of Heine's puzzle library and this book in your hands - number 43 "difficult to very difficult" and that in four finely graded difficulties - relaxation for all experts and challenge for the good ones - that's how this book is: 500 wonderful puzzles, somewhat easier than the tasks of the "difficult to extreme" bestsellers of this series.