As the title says, especially concerning novels.

The Source Material section in W20 mostly mentions your typical ghost stories. Yet I don't know if those are rally that exemplary for a large chunk of the game. I think what let's Wraith stand out and makes it special is not so much the interaction with the living(which non the less is still important) but everything that has to do with the underworld.

And for that the list I think is very lacking.
When thinking about Inspiration for that Kafkas work comes to my mind(from the body horror to the alienation...