query: SELECT ?item WHERE {
    wd:Q1304122 wdt:P910 ?category .
    ?link schema:about ?category; schema:isPartOf <https://en.wikipedia.org/>; schema:name ?title .
    SERVICE wikibase:mwapi {
       bd:serviceParam wikibase:api "Generator" .
       bd:serviceParam wikibase:endpoint "en.wikipedia.org" .
       bd:serviceParam mwapi:gcmtitle ?title .
       bd:serviceParam mwapi:generator "categorymembers" .
       bd:serviceParam mwapi:gcmprop "title" .
       bd:serviceParam mwapi:gcmlimit "max" .
      # out
      ?subcat wikibase:apiOutput mwapi:title  .
      ?ns wikibase:apiOutput "@ns" .
      ?item wikibase:apiOutputItem mwapi:item .
    }