<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2013/04/03/130403214039_bolivia_lahaya_mapa.gif>
<http://www.bbc.com/mundo/noticias/2014/04/140414_bolivia_gas_ucrania_vs.shtml>