http://xmlns.com/foaf/0.1/isPrimaryTopicOf

used by 15:

• bioimages
• dbpedia-el
• dbpedia-eu
• dbpedia-ja
• dbpedia-lite
• dbpedia-nl
• eunis
• hellenic-fire-brigade
• hellenic-police
• legislation-openuplabs
• rism
• rism-authorities
• sandrart-net
• uk-legislation-api
• zhishi-me