<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/54cac2d566afe_-_racing-balloon-01-0411-mdn.jpg>
<http://www.popularmechanics.com/flight/a6675/the-disappearance-of-the-usa-2-racing-balloon-what-went-wrong/>