query: SELECT ?item 
    (COUNT(DISTINCT ?sn) as ?count)
    (COUNT(DISTINCT ?p) as ?count_p)
    (SAMPLE(?sn) as ?sample_sn)
  {
      ?sn wdt:P407 wd:Q7737 .
      ?sn wdt:P31/wdt:P279? wd:Q101352.
      ?sn wdt:P31 ?item .
      OPTIONAL { ?p wdt:P734 ?sn }
  }
  GROUP BY ?item
  HAVING ( ?count > 0) 
  ORDER BY DESC(?count)