<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://schema.org/WebSite>
<http://www.dagoneye.it/blog/2010/04/26/facebook-open-graph-e-rdfa-il-grafo-come-modello-per-leggere-la-metapiattaforma-del-web/>