<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2014/04/27/140427155506_nadadora_en_piscina_624x351_ap.jpg>
<http://www.bbc.com/mundo/noticias/2014/05/140426_ciencia_cloro_quimico_limpieza_finde_jp.shtml>