query: SELECT ?item (COUNT(DISTINCT ?lang) AS ?count) (GROUP_CONCAT(DISTINCT ?lang; separator=',') as ?languages)
  WHERE
  {
    ?item ( wdt:P747 | ^ wdt:P629 ) ?edition .
    ?edition ^schema:about [ schema:isPartOf/wikibase:wikiGroup "wikisource"; schema:inLanguage ?lang ] .
  } 
  GROUP BY ?item 
  ORDER BY DESC(?count) 
  LIMIT 500