Here are some airmail labels from PANAGRA (Pan American - Grace Airways).
Pan American-Grace Airways, better known as Panagra, was an airline formed as a joint venture between Pan American World Airways and Grace Shipping Company. (Wikipedia)
Year: 1940, Gummed. Günter Mair's catalogue no: - ARG-B-5, rouletted VL, booklets with 5 sheets of
5(1x5), grey-red/dark grey-green/white, 3***
Year: approx.1955, Gummed. Günter Mair's catalogue no: - ARG-B-7, rouletted VL, booklets with 4 sheets of 5(1x5), dark green/yellow/white, 3***