Antarctic Campaign 1967/68, 2 covers with cachet of "Icebreaker A.R.A. Gral. San Martín", one with postmark of Antarctic station Gral Belgrano, and the other one with handstamp of the campaign, very nice!
Cover sent to Buenos Aires, with datestamp for 27/OC/61 along "BASE CONJUNTA" in dotted frame, and backstamps of "Destac. Militar esperanza" + "Oceanographic Group" in blue, rare!