<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/320x426/54cb24361d784_-_brief-history-sleds-07-1213-lgn.jpg>
<http://www.popularmechanics.com/adventure/sports/g1377/a-brief-history-of-the-sled/>