<http://schema.org/about>
"You\u2019ve undoubtedly seen estimates about the crop yields of various plants for use as biofuels. Indeed, when comparing the potential of different crops you need these numbers to make informed agriculture and renewable energy"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/renewable-energy/global-biofuel-crop-yields-often-severely-overestimated-new-research-finds.html>