Reinventing Art: Robert Rauschenberg -- #3
These are 4 places to start searching for Art History and Art movements through the late part of the 20th century.
20th Century Art
http://witcombe.sbc.edu/ARTH20thcentury.html
The Brain Bank is an Art history site
http://www.cftech.com/BrainBank/OTHERREFERENCE/THEARTS/ArtMvmtsandPeriods.html
This is a Google Search. Google offers a greate resource for Art history sites. I would also try Yahoo (www.yahoo.com) and Webcrawler (www.webcrawler.com).