query: SELECT DISTINCT ?item ?inceptionyear WHERE {
    ?item wdt:P195 wd:Q2983474 .
    ?item wdt:P31 wd:Q3305213 .
    { ?item wdt:P571 ?inception .
     BIND(year(?inception) as ?inceptionyear) .
     } UNION {
      MINUS { ?item wdt:P571 [] } . 
      ?item wdt:P170 ?creator . 
      ?creator wdt:P569 ?dob .
      ?creator wdt:P570 ?dod . 
      BIND(((year(?dod) - year(?dob))/2 + year(?dob)) as ?inceptionyear) .
      } UNION {
      MINUS { ?item wdt:P571 [] } . 
      ?item wdt:P170 ?creator . 
      MINUS { ?creator wdt:P570 [] }
      ?creator wdt:P569 ?dob .
      BIND((year(?dob) + 50) as ?inceptionyear) .
      }
    FILTER((1 < ?inceptionyear && ?inceptionyear < 1800))
  } LIMIT 4000