I guess it depends what you mean by "concepts and ideas", then. For me, the encyclopedia would cross a line, because it's talking about the plot and the charact

I guess it depends what you mean by "concepts and ideas", then. For me, the encyclopedia would cross a line, because it's talking about the plot and the characters using excerpts directly from the series, but "The Bible According To Harry Potter" is an original creative piece that Rowling shouldn't have veto power over.