query: SELECT DISTINCT ?work WHERE {
    ?work wdt:P31 wd:Q571 .
    FILTER NOT EXISTS { ?work wdt:P629 ?realwork }
    FILTER NOT EXISTS { ?realwork wdt:P747 ?work }
    ?sitelink a schema:Article .
    ?sitelink schema:about ?work .
    FILTER REGEX(STR(?sitelink), ".wikipedia.org/wiki/") .
    
    FILTER NOT EXISTS {
      ?sitelink2 a schema:Article .
      ?sitelink2 schema:about ?work .
      FILTER REGEX(STR(?sitelink2), ".wikisource.org/wiki/") .
    }
  }
  