protected function transformXML( $content, $path_to_xsl ) {

		libxml_use_internal_errors( true );
		$content = iconv( 'UTF-8', 'UTF-8//IGNORE', $content );

		$xsl = new \DOMDocument();
		$xsl->load( $path_to_xsl );

		$proc = new \XSLTProcessor();
		$proc->importStyleSheet( $xsl );

		$old_value = libxml_disable_entity_loader( true );
		$xml = new \DOMDocument();
		$xml->loadXML( $content );
		libxml_disable_entity_loader( $old_value );

		$content = $proc->transformToXML( $xml );

		$errors = libxml_get_errors(); // TODO: Handle errors gracefully
		libxml_clear_errors();

		return $content;
	}