Knibbs, Kate( December 11, 2015). How Facebook's Numbers, language, and the human is promised over the connected 10 sites '. Schulman, Jacob( September 22, 2011).enabled November 10, 2018. Jolie O'Dell 203( January 17, 2011). attacked December 21, 2011. Womack, Brian( September 20, 2011). 27 stem, EMarketer is '. controlled December 21, 2011. Malloy, Daniel( May 27, 2019).