<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/2013/01/14/130114071923_cambio_climatico_304x171__nocredit.jpg>
<http://www.bbc.com/mundo/ultimas_noticias/2013/05/130512_ultnot_cambio_climatico_biodiversidad_estudio_jg.shtml>