query: SELECT (COUNT(DISTINCT ?article) AS ?count) WHERE {
    ?article schema:isPartOf <https://en.wikipedia.org/>;
             schema:about ?item.
    ?item wdt:P31 wd:Q5;
          wdt:P21/wdt:P279* wd:Q6581072;
          wdt:P106/wdt:P279* wd:Q901.
  }