<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/2014/09/01/140901143645_alana_invitro_304x171_sciencephotolibrary.jpg>
<http://www.bbc.com/mundo/noticias/2014/09/140901_ciencia_alana_tres_padres_biologicos_np.shtml>