<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/06/54cfb8bd94936_-_future-space-nav-b-0907.gif>
<http://www.popularmechanics.com/space/moon-mars/a5041/4222146/?page=5>