Credo Reference is a good starting point. It contains hundreds of subject-specific encyclopedias & dictionaries. Quickly connect to relevant, citable and trusted resources. Use this database to look up definitions, or find topic overviews.
ARTstor is a digital library of nearly one million images in the areas of art, architecture, the humanities, and social sciences with a set of tools to view, present, and manage images for research and pedagogical purposes.
JSTOR Arts & Sciences has core scholarly peer-reviewed journals in art. For best results use Advanced Search, and check the box for Art & Art History journals. JSTOR has over 200 Art & Art History journal subscriptions.