However, if you read through the entire body of the question, it's quite clear the person asking already knows that is a potential answer. To very, very briefly summarize, it seems to me that the asker is really trying to discover which source is more authoritative in this particular instance: The Half-Blood Prince or JKR in a Q&A session. Luckily, we have a pretty great question already asking that over here (although, it has multiple answers and the highest-voted answer isn't the one accepted).
Should we consider a question to be closed as a duplicate if it requires two separate answers from two different questions in order to completely answer the question? Or should the question stand alone and receive a proper answer that draws from the information contained in the two potential duplicate questions?