<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2013/08/16/130816203012_sp_avionespia_304x171_ap.jpg>
<http://www.bbc.com/mundo/ultimas_noticias/2013/08/130816_ultnot_eeuu_cia_area51_en.shtml>