Cover sent from Marambio Base to Buenos Aires on 2/JA/1974, with special handstamp on front 'Mail carried on Air Force airplanes' in blue, and arrival backstamp of 17/JA/1974, VF!
Cover with cachet of Antarctic cruise ships 1975/76, blue handstamp of tourist ship 'Regina Prima', and postmark of the Brown Antarctic base for 26/DE/1975, very fine!
Cover sent from Tte. Matienzo Antarctic station to New York on 8/SE/1974, and returned to sender in Buenos Aires on 7/AU/1975 due to 'Addressee unknown'