Really anything. I didn't know space travel was a thing until Paul mentioned it. I only know what you mean by something sucking because Luz explained it to me. Like just in that week in that LA place, all of it was new. The fact that the ocean can be cold and the Human Realm sports and horses. All new.
And that's not entirely true, right? Maybe there isn't a 'how to be a spy' book, but there's still books about the skills you need. I mean at the very least, a book of poisons that'd work with being an assassin.