protected function doTocLicense( $post_id ) {
		$option = get_option( 'pressbooks_theme_options_global' );
		if ( ! empty( $option['copyright_license'] ) ) {
			if ( 1 === absint( $option['copyright_license'] ) ) {
				$section_license = get_post_meta( $post_id, 'pb_section_license', true );
				if ( ! empty( $section_license ) ) {

					$licensing = new \Pressbooks\Licensing();
					$supported_types = $licensing->getSupportedTypes();
					if ( array_key_exists( $section_license, $supported_types ) ) {
						return $supported_types[ $section_license ]['desc'];
					} else {
						return '';
					}
				}
			} elseif ( 2 === absint( $option['copyright_license'] ) ) {
				return '';
			}
		}
		return '';
	}