For background information, start with an exhaustive reference work such as Grove Art Online. Both the 'Guided Tour' and 'Tips for Users' (available from the Home page) provide useful information on searching Grove/Oxford Art Online.
Bibliographies located in books or at the end of journal articles can be very helpful. To learn if Pepperdine has access to a particular journal, search for the name of the journal in the library catalog, or use the 'Journals & Periodicals' search feature on the Library's Web site.
Search these online databases to find articles on your topic/artist:
Caravaggio (Michelangelo Merisi). The Musicians. ca. 1595. The Metropolitan Museum of Art. ARTstor. Web 6 Aug. 2015.
You can search ARTstor by the name of an art work, by geography, by classification (for example, architecture), or by collection (for example, Beyond the Taj). Use the Advanced Search to limit by date.
Helpful videos on using ARTstor can be found on YouTube