<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/2011/04/04/110404172859_desempleo_espana_304x171_reuters_nocredit.jpg>
<http://www.bbc.com/mundo/noticias/2014/06/140623_economia_trabajos_futuro_mj.shtml>