<http://schema.org/about>
"Austin holds its 30th annual Christmas tree recycling program in which discarded trees are mixed with sewer sludge to create the city's signature compost."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/lifestyle/recycling/blogs/when-sap-meets-sludge-christmas-tree-recycling-in-austin>