<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2014/05/01/140501134646_planeta_beta_pictoris_b_624x351_esol.calcadan.risinger.jpg>
<http://www.bbc.com/mundo/noticias/2014/05/140501_ciencia_planeta_beta_pictoris_b_dia_ocho_horas_np.shtml>