public static function getCountriesByContinent($continent='')
	{
		if (!$continent || !($gdb = self::getGeoDBO()))
		{
			return array();
		}

		$gdb->setQuery("SELECT DISTINCT country FROM country_continent WHERE LOWER(continent) =" . $gdb->quote(strtolower($continent)));
		return $gdb->loadColumn();
	}