It is a bit of a funny question. When entering a link to an external web page with a biography, discography etc. for a modern author, it is pretty easy to distinguish between an official homepage (the author himself, or somebody on his behalf edits it) and a fan page (somebody not related to the artist, and not authorized by the artist edits it). But for XVIII-century authors both choices look a bit weird. On one hand obviously there is no official homepage of J.S.Bach in the same sense as above (no web page authorised by J.S.Bach himself). On the other hand, “fan page” applied to Bach or any other XVIII-century author sounds really strange, like “Bach Museum and Arhive in Leipzig is a page created by fans of Bach”
Would you use “official homepage” for a serious web site about a particular XVIII-century author, although “official homepage” in this case definitely has a very different meaning from an official homepage of a modern author, and there could be multiple such very serious pages? If not, what type of MusicBrainz link would you use?