<http://schema.org/topics>
"american holiday,austin,Boston,Chicago,Dallas-Fort Worth,labor day,labor day weekend,Lists,Local,Los Angeles,Miami,new york,Philadelphia,San Diego,San Francisco-San Jose,summer,Politics,web"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2008/08/30/labor-day-sites/>