SELECT DISTINCT ?concept ?labelString WHERE {
      ?concept a <http://www.w3.org/2002/07/owl#Class>.
      ?concept <http://www.w3.org/2000/01/rdf-schema#label> ?label.
      FILTER (LANG(?label) = 'en')
      BIND(STR(?label) AS ?labelString)
    } LIMIT 10