Writing craft

For me one of the appeals of writing as a career, is that there's always more to learn. Many successful writers have been generous with advice. One of my favorite erotic romance authors, Emma Holly has a wonderful reading list here in case you need suggestions.

One of my all time favorites is Debra Dixon's GMC Goal, Motivation, and Conflict. Being the obsessive creature I am, I have a shelf of essential and well thumbed writing craft books.

Is there a craft book that stands head and shoulders above the rest for you?