query: SELECT ?author ?authorLabel (COUNT(?publication) AS ?count)
  WHERE 
  {
   ?item wdt:P2860 ?publication .
   ?publication wdt:P50 ?author .      
   ?author wdt:P108 wd:Q1739877 .
   SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
  } GROUP BY ?author ?authorLabel ORDER BY DESC (?count)