1921-07-02, First Flight Tsinan - Peking, pre-printed cover "By train to Tsinan and Aeroplane to Peking" with 15 C airmail and 3 C, posted Shanghai 1.7.21, arrival Peking 2.7.21 with time "14" oclock on reverse, very early airmail cover, fine
6; Flugpost; FLUGPOST INTERNATIONAL; China
6; Airmail; AIRMAIL INTERNATIONAL; China