Hong Kong. (United States - Indo-China). 1940. Air Mail envelope addressed to Saigon, Indo-China bearing United Stage SG 806, 5c light blue (pair) and Air Mail SG A852, 30c blue (2) tied by San Francisco slogan 'Aug 13 40' , endorsed 'via Clipper' routed via Hong Kong with 'Passed by Censor/ Hong Kong/ 9' cachet in blue and Victoria transit '23rd Aug' and Hanoi '28/8' and Saigon arrival '30th Aug' on reverse.