Yeah, Godheval's advice is pretty sound. If there are enough reliable sources to warrant a separate article, go for it. If there is only a little information about the series out there, compiling it into a single article may be the best bet. It's really up to what you think would look best- generally, if there are at least a couple of sources (like reviews, or news stories about the book) then a separate article works best. I know nothing beyond the series beyond the basics (I work in a bookshop) so I can't really give an opinion on this series specifically at the moment. I'd be happy to give my opinion on/help improve an article if you write one.