<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/2013/01/03/130103014849_sp_giraffes_fight_2_304x171_bbc.jpg>
<http://www.bbc.com/mundo/noticias/2013/01/130102_ciencia_jirafas_comportamiento_tsbdietas.shtml>