<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/2013/12/12/131212123126_cueva_sumatra_tsunami_464x261_ap.jpg>
<http://www.bbc.com/mundo/noticias/2013/12/131212_ciencia_tsunamis_secretos_historia_cueva_sumatra_np.shtml>