1. Duke "Classic" Library Catalog - always use the old ("Classic") version for better and more accurate searching
Use your natural language to find ONE book that's relevant. Then go into the record and click the subject headings assigned to that book to find more like it.
These are all library subject headings
2. Worldcat - combined catalog of all libraries
Use Worldcat to locate exhibition catalogs and books for interlibrary loan and archives of collections. There's a "libraries with this item" link that shows NC libraries first.
3. Virtual Catalogue for Art History (www.artlibraries.net) - consortial catalog of the large specialty art libraries (mostly art museums libraries), including Met, MoMA, and major foreign institutions. Helpful because subject is only art(s); interlibrary-loan is not possible, but this catalog confirms the existence of items possibly obtainable through other methods.