THE best book depends on your personal skill set when it comes to working with computers, relational databases and FileMaker. You may want to search out titles in a site like Amazon and check out the reader reviews to get a better idea as to which is most appropriate for you.
Like Phil mentioned, it's a preference that depends on your level of understanding.
But I can give a great recommendation - http://www.fmptraining.com/
Jerry Robin is an amazing presentor and teacher. I've taken some of his classes in the past and have helped a great deal.
If you're looking specifically for a physical book, then this won't help you much. But it you wanted good overall training, this would be a great resources.