ChinaCovers and CancellationsAirmail1937 (9 Apr.) first flight cover from Pakhoi to Canton on "South Western Aviation Corp/ - Direct Through Service./Hanoi - Pakhoi - Fort Bayard - Canton" bearing 30c. franking tied by Pakhoi bilingual c.d.s. (the latest recorded date of use of this postmark) with Canton (11.4) backstamp. Muller 87. Photo