<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef-1.bbci.co.uk/news/560/media/images/74103000/jpg/_74103646_c0180342-thymus_and_lymphatic_vessels,_artwork-spl.jpg>
<http://www.bbc.com/news/health-26920528>