<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://pop.h-cdn.co/assets/cm/15/06/640x430/54cfcfe46605c_-_science_mysteries_02_0111-xl-23571137.jpg>
<http://www.popularmechanics.com/science/g137/sciences-greatest-unsolved-mysteries-progress-report/>