You're Not Really Following @BarackObama on Twitter - Philip Bump - The Atlantic Wire
http://www.theatlanticwire.com/politics/2013/04/youre-not-following-barackobama-twitter/63930/

Twitter Followers For Sale - NYTimes.com

http://www.nytimes.com/2012/08/23/fashion/twitter-followers-for-sale.html