the limits of appropriation?

http://www.guardian.co.uk/world/2011/mar/23/richard-prince-artwork-copyright-breach

http://www.patrickcariou.com/rasbook.html

http://bigthink.com/ideas/31757

http://www.artinfo.com/news/story/37352/why-patrick-carious-legal-triumph-over-richard-prince-and-gagosian-is-a-victory-for-artists/