For background information, start with 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. Oxford Art Online also includes the Encyclopedia of Aesthetics and The Oxford Companion to Western Art.
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.
These online sources include articles about art, art history, history, and culture.