<http://schema.org/topics>
"Business,coca cola,features,hashtag,Marketing,Mashable,Promoted Accounts,promoted trends,Promoted Tweets,Social Media,Social Media 101 Series,Twitter,Twitter Lists,volkswagen"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2011/06/22/twitter-marketing-guide/>