- $book->addChapter('Notices', 'Cover2.html', $content_start . $this->getExportInformation('PHPePub') . $bookEnd);
+ // Could also be the ISBN number, prefered for published books, or a UUID.
+ $hash = sha1(sprintf('%s:%s', $this->wallabagUrl, implode(',', $entryIds)));
+ $book->setIdentifier(sprintf('urn:wallabag:%s', $hash), EPub::IDENTIFIER_URI);