<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2013/04/09/130409110133_vietnam_economy_paddy_field_464x261_reuters.jpg>
<http://bbcvietnamese.com/vietnamese/vietnam/2013/04/130412_vn_social_stratification.shtml>