<http://schema.org/about>
"We all know that the amount of greenhouse gas emissions varies widely whether you're taking a bus, a train, or flying; by the fuel efficiency of your car and by how many people are in the vehicle. But one thing which"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/cars/gap-between-train-airplane-environmental-impact-narrows-in-new-life-cycle-analysis.html>