Best wordpress book (In your opinions!)

Hi, I’m looking for a really good book about WordPress. But to quantify that a bit more, i’m a relative beginners and a graphic designer. I’m really into themes. And need a book that can help me work with themes better. Im not much of a coder, but have a website and understand the main elements and can update it etc. So i’m looking for recommendations about great books that teach you how to work with themes and avoid going into too much code. Many thanks in advance. Pete