Bernard-
 
In the Resource Collections at the Getty we had a 2-volume list of European
museums and galleries that was published in Germany.  It was not comprehensive
(and in German, which was limiting for many people) but it was helpful.  I can
track it down or you can possibly call (or e-mail) someone at the Center
Library directly.
 
Leslie Johnston
Historic New Orleans Collection
[log in to unmask]