<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/54cada62b2ea1_-_cng-conversion-01-0212-mdn.jpg>
<http://www.popularmechanics.com/cars/how-to/a7487/should-you-convert-your-car-to-natural-gas/>