<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef-1.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2013/01/04/130104142456_2rA_os.jpg>
<http://www.bbc.com/mundo/video_fotos/2013/01/130104_galeria_rios_del_mundo_argentina_granbretana_jbo.shtml>