From time to time, auction houses offer Zeppelin covers from the Belgian Congo. The price paid for such items is generally far higher than similar covers from the Netherlands or even Belgium - the reason being that between 1932 and 1939 only 15 flights carried mail originating from the Congo.
Apart from the early overprints in 1929, the first airmail stamp design for Nicaragua was the well known ‘aeroplanes flying over the volcano of Momotombo’. Now the American Navy was in Nicaragua at the time for reasons to prop up the regime and they had one aeroplane a DH-4s.
Mr. T. A. Melville, Acting Director of Posts and Telegraphs in the Federated Malay States, who was for many years in the Post Office Department of the Straits Settlements, has contributed a valuable history of the Straits Settlements Post Office to the voluminous centenary work, "One Hundred Years of Singapore".