Auction # 2419 WORLDWIDE + ARGENTINA: Special May auction

Cover sent from Buenos Aires to "Port Stanley - Falkland Islands" on 31/JUL/1988, with the mark "Declaración Conjunta - 3", it was returned to sender from the Central Argentine Post Office because the name was indicated as "Falkland Islands" instead of "Islas Malvinas", with rare mark: "Devuelto por aplicación de lo establecido en el artículo 24 de la constitución de la Unión Postal Universal", very interesting!