query: SELECT DISTINCT ?item ?itemLabel ?start ?end ?district ?districtLabel ?group ?groupLabel WHERE {
    ?item p:P39 ?mem.
    ?mem ps:P39 wd:Q654291.
    ?mem pq:P2937 wd:Q28976204.
    OPTIONAL { ?mem pq:P580 ?start. }
    OPTIONAL { ?mem pq:P582 ?end. }
    OPTIONAL { ?mem pq:P768 ?district. }
    OPTIONAL { ?mem pq:P4100 ?group. }
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
  }