public function actionGetFirmsForSubspecialty()
{
if (!($subspecialty = \Subspecialty::model()->findByPk(@$_GET['subspecialty_id']))) {
throw new Exception('Subspecialty not found: ' . @$_GET['subspecialty_id']);
}
echo \CHtml::dropDownList('firm-id', '', \Firm::model()->getList($subspecialty->id), array('empty' => 'All firms'));
}