AH, yes! Here's a wonderful resource: the Getty Center collection. Enjoy a nice browse here:
http://links.creativelive.com/e/viewInBrowser?index=56714dbac3234bb19b205551420316f8&email=sandywatercolorinfo%40gmail.com&messageId=1b96fe4633684ecd9d14b8c6c6b60c7e