When searching for books in Power Search, filter by Resource Types → Books. Results will include both print books and ebooks.
Many art/architecture books have indexes in the back. These enable you to look up an artwork/building/place/person/etc. and find the page number on which it is mentioned. Be aware which index you are looking at—many books have separate indexes for photos/illustrations!
When searching for art-related books, you may run across exhibition catalogs. These are books that document works featured in specific shows/exhibitions in museums or galleries. Many exhibition catalogs include scholarly essays, bibliographies, and photos, making them excellent sources for your research.