Here are unlisted labels in a catalog. This is a small sheet of 3 airmail labels from Austria (i believe),
It looks like it was issued for inaugural flights with Austrian Airlines and Lufthansa. The first is for flight Wien-Praha-Dusseldorf, second for Dusseldorf-Wien and last one for Munchen-Koln-New York.
Year: ?, Gummed. Günter Mair's catalogue no: - AUT-C-?, imperforated, sheets of 3(1x3), dark blue or grey-blue/white,