protected function doCopyrightLicense( $metadata, $title = '', $id = 0, $section_author = '' ) {

		if ( ! empty( $section_author ) ) {
			_deprecated_argument( __METHOD__, '4.1.0' );
		}

		try {
			$licensing = new \Pressbooks\Licensing();
			return $licensing->doLicense( $metadata, $id, $title );
		} catch ( \Exception $e ) {
			$this->logError( $e->getMessage() );
		}
		return '';
	}