Cuba 1948 (Dec.28th) - Sc 431 (EDIFIL 418) FDC.
This is a block of 4 of the stamp issued to celebrate the First Pan-American Congress of Pharmacy in Havana on a cacheted, unaddressed First Day Cover. The Official handstamped cachet was applied on the reverse. As it happened very frequently in Cuba, this stamp was issued almost three weeks after the Congress had taken place, from Dec. 1st to Dec. 8th. Mejor tarde que nunca or Better late than never!