Indochina, 40th Anniversary of the Discovery of Radium, October 24th, 1938, Michel Nr. 231; A single stamp with a nominal value of 18C and a 5C surcharge was issued in perforation 13. Given the surcharge and the fact that the country’s inhabitants were still poor this stamp was basically only purchased for philatelic purposes and found little non-philatelic use.
Here is the mint hinged stamp.
Registation Nr. 090230