<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/06/54cfc7d2b795e_-_pergola-rafters-2-470-0409.jpg>
<http://www.popularmechanics.com/home/how-to-plans/how-to/a6345/4314676/>