CHINA - Yunnan. 1948 registered airmail 'On Postal Service' cover from Yunnan (despatch c.d.s. on registration slip on reverse-torn away) to Nanking. Showing 2 wax seals of the 'Director of Yunnan District Head Post Office' and two Nanking receivers. This is an overprinted 'On Service' cover on the standard domestic envelope sold by the P.O. and is actually an Official Postal Stationery, without postage marking - perhaps should be listed in the Official Postal Stationery of China. (Photo). Est. 150 - 200 CHF.