1. Lenhart A (2009) Adults and Social Network Websites. http://pewinternet.org/Reports/2009/Adults-and-Social-Network-Websites.aspx?r=1 . Accessed May 3, 2011.
2. Facebook (2010) Press Room-Statistics. http://www.Facebook.com/press/info.php?statistics . Accessed May 3, 2011.
3. Hitwise (2010) Top 20 sites and engines. http://www.hitwise.com/us/datacenter/main/dashboard-10133.html . Accessed May 3, 2011.
4. Lenhart A (2009) The Democratization of Online Social Networks: A look at the change in demographics of social network users over time. Pew Internet & American Life Project. http://pewinternet.org/Presentations/2009/41--The-Democratization-of-Online-Social-Networks.aspx . Accessed May 3, 2011.
5. Hawn C. Take two aspirin and tweet me in the morning: how Twitter, Facebook, and other social media are reshaping health care. Health Aff (Millwood). 2009;28(2):361–368.