getType() !== 'journal_article') { throw new NotFoundHttpException(); } $citation_tools = new CitationTools($this->entityTypeManager); $citation_metadata = $citation_tools->getCitationMetadataForArticle($entity); $citation_metadata['type'] = 'journal_article'; $r = Reference::create($citation_metadata); return parent::export($bibcite_format, 'reference', $r); } }