That is an interesting question. Yes, it in the example 'refers' does mean 'about', BUT you can't use it like that in general, and I'm not sure I can properly explain the difference. If the book, or the movie are ABOUT that topic, you can't say they REFER to that topic. A reference is when you mention something that has relevance to the whole thing. So, if a movie was about (say) the hippie movement in the USA, you could say it referred to the war, in terms of how the war affected the behaviour of the hippies. If the book was about astronomy, you could say that it refers to mathematics, to explain the movement of the planets. The report could only refer to the GDP of Korea, if it was about something else, perhaps the economics of China?