there are few problems in this book. This book may be good for a graduate level students. but it is far advanced for an introductory course. First, author did not explain very sign in an equation. it seems author expects readers to know each sign automatically. I feel like I need to go over the book in order to find what the sign means. second, in the text, author mentioned about wave function. and he gives a brief explaination about it. In my opinion, a brief introduction is not enough. he should also include a complete reference in the book talking about wave function. Thrid, and the worst, author did not give a clear explaination for example. It is not step by step. Reader needs to be very intelligent to apply and understand the approach in example. In later part of problems, he gives a question that he did not really mention about it. I always feel the best book is a book that is most clear and comprehensible. This book is not.