I collect nice covers from world-wide.
The nice cover depict world -beautiful
mankind and commemorative events.
I found some stamps of 1974 at https://www.tripleclicks.com/15258834/detail.php?item=211908 .These are the stamps from 1974 but I don't which country stamps are these. Can you tell me which country cover are these and how to know these are really from 1974?