<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/06/54cfc5b8b7f96_-_pm-apollo-toc-6-470-57680182.jpg>
<http://www.popularmechanics.com/space/moon-mars/a4263/4317729/>