public function init($citationAsArray = false)
    {
        self::$context = new Context($this);
        self::$context->setLocale(new Locale\Locale($this->lang)); //init locale
        self::$context->setCitationsAsArray($citationAsArray);
        // set markup extensions
        self::$context->setMarkupExtension($this->markupExtension);
        $this->styleSheetXml = new SimpleXMLElement($this->styleSheet);
        $this->parse($this->styleSheetXml);
    }