<http://schema.org/about>
"On the surface, NASA's storied space shuttles appear to be priceless, but there is a very real price tag associated with the iconic winged spaceships."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/how-much-are-nasas-space-shuttles-worth>