prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix ex: <http://example.org/survey-sample/ontology/>
prefix acm: <http://daml.umbc.edu/ontologies/topic-ont#>
prefix dc: <http://purl.org/dc/elements/1.1/>

SELECT ?who WHERE
{
  [ rdf:subject ?work;
    rdf:predicate ex:isAbout;
    rdf:object ?topic
  ] dc:creator ?who
}