query: SELECT distinct ?item ?subject ?subjectLabel  ?DOI WHERE {
    ?item wdt:P123 wd:Q57971890.
    OPTIONAL { ?item wdt:P921 ?subject. }
    OPTIONAL { ?item wdt:P356 ?BookDOI. }
    BIND(URI(CONCAT("https://doi.org/", ?BookDOI)) AS ?DOI)
    SERVICE wikibase:label {
      bd:serviceParam wikibase:language "sv".
      bd:serviceParam wikibase:language "en".
    }
  }
  ORDER BY ?subjectLabel