<https://secure.gravatar.com/avatar/17190d39d64c4301b8747fdd754cadaa?s=96&d=blank&r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://news.sap.com/germany/2011/09/sap-kauft-anbieter-von-b2b-netzwerken-crossgate/>