The Sense of Style: The Thinking Person's Guide to Writing in the 21st Century - Steven Pinker
I read this book as a non-native English speaker and enjoyed it very much. It is very well-written and clear enough. If you are a linguist or interested in languages, potentially it will be one of your favorite books. As a Ph.D., one of the most important benefits I got was to understand that there are several ways to structure my sentences when writing a manuscript; for instance if I want to sell/reflect an important idea, I should be careful with 'the one' sentence I choose, otherwise it might be reflected wrong or complicated. As a writer, you should be able to do empathy with the reader because it helps you to understand what to write and how to write your book (or in my case; your manuscripts). All in all, I want to say, you can learn a lot from this book.