public function getNgMedicalReference($con = null)
 {
     include_once 'lib/model/om/BaseNgMedicalReferencePeer.php';
     if ($this->aNgMedicalReference === null && $this->ng_medical_reference_id !== null) {
         $this->aNgMedicalReference = NgMedicalReferencePeer::retrieveByPK($this->ng_medical_reference_id, $con);
     }
     return $this->aNgMedicalReference;
 }