<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2012/05/26/120526022417_vaticano_304x171_getty_nocredit.jpg>
<http://www.bbc.com/mundo/noticias/2013/04/130411_tecnologia_fantasias_vaticanas_aa.shtml>