It is a really good book for you study English. In this book you can study how to speak English and many grammatical points of English language which are very important. This book is more than 40 mb, so it may take you a little long time to download. And the book is also designed for self-study. You can learn by yourself without any teachers to guide you because the book will be a teacher for you.
This is the book I personally prefer to use when I think I need a grammar check up for my essays or letters, or anything which is about English grammar. This book has two parts, part one and two. For those of you who do not have intermediate level knowledge of English grammar, i recommend that you study part one first because in that book you’ll learn a lot about basic grammar points which are really necessary to improve your English to the next level.