<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/05/320x240/54cb07b956360_-_bho-lightbulb-07-0213-de.jpg>
<http://www.popularmechanics.com/technology/gadgets/g1096/a-brief-history-of-the-lightbulb/>