http://www.mckinseyquarterly.com/article_page.aspx?ar=1763&L2=21&L3=114
http://www.mckinseyquarterly.com/article_page.aspx?ar=1638&L2=21&L3=37
http://www.mckinseyquarterly.com/article_page.aspx?ar=1506&L2=3&L3=50
http://www.economist.com/opinion/displaystory.cfm?story_id=10491077