<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef-1.bbci.co.uk/news/560/media/images/70614000/jpg/_70614367_coloured_sem_of_bone_marrow_tissue-spl-1.jpg>
<http://www.bbc.co.uk/news/health-24609025>