References:

• Sheahan, J., Spencer, S., Matzan, J. (2014) Social eCommerce: Increasing Sales and Extending Brand Reach. Beijing: O’Reilly Media
• Safko, L. (2010) The Social Media Bible: Tactics, Tools, and Strategies for Business
  Success. 2nd Edition. John Wiley & Sons.
• https://support.google.com/webmasters/answer/35291?hl=en