Yes I did indeed. I bought a book of faces for reference since I find it a totally bitch and a half to find some of what I want on the Internet. I also bought a book on drawing light and shade because I really want to find a way to add more depth to my pictures. I'm kind of lazy and inconsistant with this, however, I think the light and shade influenced my most recent canon drawing, particularly with respect to how I colored or shadowed Snape's face.