World Exhibition Liege / Luik
Airplane - Airline Lufthansa - Stamp exhibition
Balloon race Coupe Andries Blitz - Nijmgen - Aachen
Dan Air Airlines - Compass
Sweden - Netherlands
German Air Shipping Company - Hamburg America Line
Rotary Wing Aircraft - Helicopter - Pioneer Flight - Auto ...
Rotary Wing Aircraft - Helicopter
FFC / First Flight Card Austria - USA - Philatelic ...
By-KLM-Dutch-Airmail
