KV)1961 ARGENTINA, ”GLIDER” ENVELOPE COMMEMORATING THE FIRST GLIDER FLIGHT THAT LEAVES FROM BUENOS A

KV)1961 ARGENTINA, "GLIDER" ENVELOPE COMMEMORATING THE FIRST GLIDER FLIGHT THAT LEAVES FROM BUENOS AIRES AND IS ADDRESSED TO LA PLATA, WITH STAMPS OF THE MONUMENT TO GENERAL JOSÉ DE SAN MARTÍN IN MADRID AND OF MARIANO MORENO WITH A BUILDING, POSTMARKS OF "BUENOS AIRES NOV 18, 1961 PHILATELY".