=SIERREUR(INDEX($B$2:$K$2;PETITE.VALEUR(SI($B3:$K3=M$2;COLONNE($B$2:$K$2)-1);1));"")&SIERREUR(","&INDEX($B$2:$K$2;PETITE.VALEUR(SI($B3:$K3=M$2;COLONNE($B$2:$K$2)-1);2));"")&SIERREUR(","&INDEX($B$2:$K$2;PETITE.VALEUR(SI($B3:$K3=M$2;COLONNE($B$2:$K$2)-1);3));"")&SIERREUR(","&INDEX($B$2:$K$2;PETITE.VALEUR(SI($B3:$K3=M$2;COLONNE($B$2:$K$2)-1);4));"")