Books that it would be either difficult, unlikely, or impossible to picture as having a film version. This can be due to amount of explicit content, the author banning a film from being made, lack of story or possible storylines, obscurity, or it just would suck as a movie. It's your call. The book can be good, bad, or too strange for description.

Please make sure it DOES NOT have a movie adaptation in any language or medium before adding it! We'd all prefer the Percy Jackson movies didn't exist, but they still exist. You would also be surprised at what DOES have a movie version.