For background information, start with an exhaustive reference work such as Grove Art Online. Both the 'Guided Tour' and 'Tools and Resources' (available from the Home page) provide useful information on searching Grove/Oxford Art Online. The Oxford Companion to Western Art edited by Hugh Brigstocke is also part of Oxford Art Online.
To place art and architecture in context, consult Art and Humanities Through the Eras
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 'Access Databases and E-Journals' search feature on the Library's Web site.