/**
  * Fonction permettant de partir d'un numero de reference de retrouver la facture correspondante
  * 
  * @param string $num_reference le numero de reference 
  * 
  * @return CFactureEtablissement
  **/
 function findFacture($num_reference)
 {
     $facture = new CFactureEtablissement();
     $facture->num_reference = $num_reference;
     $facture->loadMatchingObject();
     return $facture;
 }