Advanced PIC books?

There are several threads about beginner pic books, but I'm wondering about advanced ones that treat you like an engineer taking a college class on pic programming. It hasn't been too hard to find a means of doing any given task with a Google search, but now I would like to develop a more solid professional understanding of the proper way to use micro controllers. I work primarily with 18F chips, a junebug pickit 2 clone and microchip C18, but I would be willing to use how and when to use assembly. Being an college student I know that some textbooks are all fluff, so I would like a recommendation for a good professional level book that gives the most complete and usable background, development process and application of pic chips possible.

Thanks