Greece: H.E.E.S airmail labels

Here are an airline issue labels from H.E.E.S (Helliniki Eteria Enaerion Synghinonion) =
S.H.C.A (Societe Hellenique de Communications Aeriennes).

Year: 12.11.1931, Gummed. Günter Mair's catalogue no: - GRC-B-1a, imperforated, 
violet-blue/pink, 5*****

Year: 1931, Gummed, Günter Mair's catalogue no: - GRC-B-1b, imperforated, 
blue or bright blue/white, 5*****