PREFIX pubann:<http://pubannotation.org/ontology/>
SELECT ?s1
WHERE {
  GRAPH prj:CORD-19-Diseases-PubDictionaries {
    ?o1 tao:denoted_by ?s1 .
    ?o1 a <http://purl.obolibrary.org/obo/MONDO_0005091> .
  }
}