<http://schema.org/mainEntityOfPage>
<http://blogs.wsj.com/speakeasy/2014/04/03/david-letterman-calls-it-quits-video/>
<http://blogs.wsj.com/speakeasy/2014/04/03/david-letterman-calls-it-quits-video/?mod=WSJ_ArtsEnt_Speakeasy>