This book helps you to understand the logic of the language, which is often implicit and hard to grab and answers any question you have (it is also modified regularly so don't worry for being outdated).I was recommended this book by my English teacher and bought it - almost ten years ago. It is not a big book and was very useful to read through in the first place. Ten years on, I still go back to it when I have some questions on grammar.
If you don't have your reliable grammar book, definitely go for this one .
