query: SELECT ?errata ?errataLabel ?itemLabel ?item
  WHERE 
  {
    hint:Query hint:optimizer "None" .
    ?errata wdt:P31 wd:Q1348305 .                  # ?errata is an errata
    filter not exists {?itemZ wdt:P2507 ?errata . } # there's no ?item pointing to the errata.
    ?errata rdfs:label ?errataLabel . filter(lang(?errataLabel)="en")
    filter(strstarts(?errataLabel,"Erratum to:"))
    bind(replace(?errataLabel,"Erratum to: “","") as ?111) .
    bind(strbefore(?111,"”") as ?222) .
    bind(replace(?222,"”","") as ?itemLabel) .
    ?item rdfs:label ?itemLabel.
    filter(strlen(?itemLabel)>20)
    filter(?item != ?errata)
  }