query: # Authors of multiple works that do not have a main subject statement
  SELECT DISTINCT ?item (COUNT(?work) AS ?count) (SAMPLE(?work) AS ?pub) WHERE {
   { 
    SELECT DISTINCT ?work 
                    WHERE  {
                      ?work wdt:P31 wd:Q13442814 .
                      }
    LIMIT 20000
   } 
    MINUS { ?work wdt:P921 ?topic . }
    ?work wdt:P50 ?item  .
  }
  GROUP BY ?item
  ORDER BY DESC(?count)
  LIMIT 200