<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/320x160/54cafb380b8e0_-_steam-engines-01-1112-de.jpg>
<http://www.popularmechanics.com/technology/g987/a-brief-history-of-the-steam-engine/>