<https://secure.gravatar.com/avatar/45b63f86e09fb2281be086476da9c8cb?s=96&r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.exeideas.com/2014/01/7-best-practices-when-marketing-via-SM.html>