public function getCountriesISO()
    {
        if ($this->_aCountriesISO === null) {
            $oDb = \OxidEsales\Eshop\Core\DatabaseProvider::getDb();
            $this->_aCountriesISO = [];

            $sSelect = "
                SELECT
                    `oxcountry`.`oxisoalpha2`
                FROM `oxcountry`
                    LEFT JOIN `oxobject2delivery` ON `oxobject2delivery`.`oxobjectid` = `oxcountry`.`oxid`
                WHERE `oxobject2delivery`.`oxdeliveryid` = " . $oDb->quote($this->getId()) . "
                    AND `oxobject2delivery`.`oxtype` = 'oxcountry'";

            $rs = $oDb->getCol($sSelect);
            $this->_aCountriesISO = $rs;
        }

        return $this->_aCountriesISO;
    }