The problem with this book is that it has several mistakes on it, algebraic mistakes especially. This is the reason because I put 4 stars only . On the other hand, it is difficult to find books like this, I mean with a huge variety of exercises including difficult ones. So I think that this book is good in order to prepare exams or just develop practice. I bought only the solution book, and I like this book because it includes the questions as well. Not as happen with several books where the authors force you to buy the theory book.