<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ichef.bbci.co.uk/news/ws/560/amz/worldservice/live/assets/images/2013/12/04/131204101654_google_plus_blog_624x351_reuters.jpg>
<http://www.bbc.com/mundo/blogs/2013/12/131204_blog_un_mundo_feliz_david_cuen_google_plus.shtml?postId=118081469>