<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/2014/01/03/140103204804_bici_polo_pies_cubiertos_304x171_coleccionjuanmenendezgranados.jpg>
<http://www.bbc.com/mundo/blogs/2014/01/140103_blog_polo_sur_campo_sastrugi.shtml>