International Direcotory of ArtsDeGruyter
Updated annually.
"[C]ontains about 143,000 addresses from all over the world: from museums and public galleries, universities, academies and schools, associations, the art trade, galleries, auctioneers, restorers, art publishers, art journals, antiquarians as well as art and antiquity fairs. The names of curators and senior academic museum staff as well as indexes of companies and persons are included." [home page]