<http://schema.org/about>
"In true 21st century fashion, Al Gore doesn't stop at the printing press when it comes to offering his book, Our Choice, to the masses. Taking a cue from the popularity of both digital books and apps,"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/clean-technology/al-gore-launches-interactive-digital-book-app-about-climate-crisis-interview.html>