Belgian Congo: Airmail labels 2

Here are more airmail labels from Belgian Congo. The first airmail label issued there and incomplete
sheet of 28.

Year: 9.1928, Gummed. Günter Mair's catalogue no: - BCO-A-1, perforated 11 ½, booklets with 10
sheets of 50(5x10), dark blue/white, 5*****

Year: Year: 1936, Gummed. Günter Mair's catalogue no: - BCO-A-2b, perforated 11 ½, sheets of 
100(10x10), dark blue/white, 3***