query: SELECT
    ?item ?title
    (CONCAT("[[",strafter(str(?item), "y/"),"|", ?title, "]]") as ?l) 
    (CONCAT("[",str(?ws)," ", ?wst,"]") as ?wsp)
    ?subject ?vol ?pages ?page
  WHERE
  {
      hint:Query hint:optimizer "None".
      VALUES ?vol { "1" "2" "3" "4" "5" "6" "7" "8" }
      ?item wdt:P1433 wd:Q665807 . 
      ?item wdt:P478 ?vol . 
      ?item wdt:P304 ?pages . 
      OPTIONAL { ?item wdt:P1476 ?title } . 
      OPTIONAL { ?item wdt:P921 ?subject } . 
      MINUS { ?item wdt:P31 wd:Q1302249 }
      BIND( xsd:integer(strbefore(CONCAT(REPLACE(?pages,"[a-z]",""),"-"), "-")) as ?page) 
      OPTIONAL {  ?ws schema:about ?item ; schema:name ?wst ; schema:isPartOf <https://de.wikisource.org/> }
  }
  ORDER BY xsd:integer(?vol) ?page ?pages ?title