query: #Which publication is cited the most? Counting publications that cite other publications (expressed with p2860)
  SELECT ?publication ?publicationLabel (COUNT(?publication) AS ?count)
  WHERE
  {
  	?item wdt:P2860 ?publication .
  	SERVICE wikibase:label {
  		bd:serviceParam wikibase:language "en" .
         ?publication rdfs:label ?publicationLabel
  	}
  }
  GROUP BY ?publication ?publicationLabel
  ORDER BY DESC(?count)
  