Reading about your topic in a specialized encyclopedia, dictionary, or handbook may be one of the most effective and time saving research tips. These resources can help you define unfamiliar terms, understand the parameters of current debate in a particular area and provide you with a preliminary bibliography on the subject. Listed here are a few sources to get you started.
The online database includes The Oxford Companion to Western Art, The Encyclopedia of Aesthetics, and The Concise Oxford Dictionary of Art Terms.
Oxford Reference Online: Art & Architecture
Encyclopedia of African American Artists by 
The Public Domain: How to Find & Use Copyright-Free Writings, Music, Art & More by 
