query: #title: Reference should generally have a reference url as well
  # Complex constraint from [[Property talk:P6333]]
  # [[Property:P854|reference URL&#32;<small dir="ltr">(P854)</small>]] would generally be present
  SELECT DISTINCT ?item ?p ?title_of_broader_work
  WHERE
  {
    ?ref pr:P6333 ?title_of_broader_work .
    MINUS { ?ref pr:P854 ?refurl }  .
    ?st prov:wasDerivedFrom ?ref . 
    ?item ?p ?st
  }
  LIMIT 100