<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/54c8276e4b92b_-_pmx0306tree020_large.jpg>
<http://www.popularmechanics.com/home/how-to-plans/how-to/a540/2456277/>