Seems quite evolved. Dorothy L. Sayers Society Site for enthusiasts and fans with lots of useful links and contacts. Site is in French. Site in English, quite easy to use. ABAC Antiquarian Booksellers' Association Of Canada.
Site is in French and English.
The Danish Antiquarian Booksellers Association. Site is in Dutch and English. Small site in Finnish and English. Site in German only. ABA British based international association.