<http://schema.org/topics>
"apps,back to school,bigwords,cram,dictionary.com,evernote,Facebook,iPhone,iPhone Resource Lists,istudiez pro,Lists,Mashable,myhomework,pi83,simplemind,Social Media,wikipedia"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2009/08/25/back-to-school-iphone/>