public function getArticles()
    {
        if (is_null($this->_aArtIds)) {
            $oDb = \OxidEsales\Eshop\Core\DatabaseProvider::getDb();
            $sQ = "select oxobjectid from oxobject2delivery where oxdeliveryid=" . $oDb->quote($this->getId()) . " and oxtype = 'oxarticles'";
            $aArtIds = $oDb->getCol($sQ);
            $this->_aArtIds = $aArtIds;
        }

        return $this->_aArtIds;
    }