Practical Italian Grammar by Joseph Louis Russo [Leatherbound]

If you are looking for a book to supplement your study of L'italiano secondo il metodo natura and other direct/nature method Italian courses, Practical Italian Grammar by Joseph Louis Russo is a handy pick. This book introduces the Italian grammar progessively with abundant drills and exercises. What you learn implicitly via comprehensible input can be made into explicit knowledge via this precious book. In short, you can use this book, so to speak, to smoothen your Italian and using the drills and exercises actively practice it. You can preview the book here.