Madagascar: Airmail labels

Here is my first label from this country.

Year: 1937, Ungummed. Günter Mair's catalogue no: - MDG-A-3d, perforated 11, sheets of 30(3x10)
ref.: "P.T.T. MADAGASCAR   E. N° 131" with varieties: P.T.T/P.TT/PT.T./P.T.T./EN°/EN.°/E.N.°
black/grey-blue, 4****