http://www.investopedia.com/ask/answers/120114/how-does-facebook-fb-make-money.asp

http://www.thecultureist.com/2012/08/13/buying-followers-on-twitters-black-market/

https://www.entrepreneur.com/article/251108

http://www.truth-out.org/news/item/22158-unintended-and-anti-social-consequences-of-social-media-use

http://www.theguardian.com/media-network/2015/may/21/customer-complaints-social-media-rise