Angola: Full sheet of airmail labels

Here is my first airmail label from Angola. It's a complete sheet of 70 labels.

Year: approx.1975, Ungummed. Günter Mair's catalogue no: - ANG-A-7b, imperforated, sheets of 70(7x10), ref.: "AV22 459", light grey-blue or light blue or light greenish blue, 2**