query: SELECT ?item ?group ?start_time ?end_time
  WHERE {
  ?item p:P39 ?node.
    OPTIONAL { ?item p:P734 ?family_name }
    ?node ps:P39 wd:Q18887908
    OPTIONAL { ?node pq:P580 ?start_time }
    OPTIONAL { ?node pq:P582 ?end_time }
    OPTIONAL { ?node pq:P4100 ?group }
  
  
  }
    ORDER BY ASC(?family_name)