Oxford Art OnlineA great starting point for research, Oxford Art Online is an encyclopedia of art, architecture, and art history that you can use for its articles, plus the bibliographies at the end of each article could point you in other research directions.
Tips on searching Oxford Art Online:
1. This resource actually includes three separate resources: The Grove Dictionary of Art (an encyclopedia with fairly comprehensive entries), The Oxford Companion to Western Art (more succinct entries, only covers Western art), the Encyclopedia of Aesthetics (focuses more on aesthetics and critical approaches), and the Concise Oxford Dictionary of Art Terms (pretty much exactly what it sounds like). If one of these is more relevant to your search, you can limit your search to that one source.
2. For many articles, when you view the page, you will see a tab at the top that says "Images." This tab will take you to a page of links that will direct you to images that relate to your article.
3. There may also be a tab that says "Related Content," which will direct you to other articles in Oxford Art Online system with similar stuff.