Sketching for the fine artist?

You know, I wish someone would write a book about sketching for the fine artist. So many books are dedicated to the technique side of sketching/drawing, but I have yet to find one that focuses on creativity and developing ideas through sketching, or, at the very least, drawing for paintings (which I feel is very different than just drawing). I would even be happy if I found a book where artists were discussing their process.. If anyone knows of a good book, let me know. :P It's one of those things that's been driving me nuts for a while now.