The following four American museums have published Wwii Era Provenance information for selected artwork online in PDF files.

Freer Gallery of Art and the Arthur M. Sackler Gallery of the Smithsonian Institution (PDF dated 9/10/2013 published on internet: Archived version here)

Philadelphia Museum of Art List of Collection Works That Changed Ownership In Continental Europe, 1933-1945 - no images (Archived version here)

Tacoma Art Museum (PDF published on the internet  in 2015: Archived version here)

Toledo Museum (PDF dated 2006: Archived version here)

To search in files, clink on link and hit Ctrl-F to call up the search box.