Covers: Romania Image Description History Pre-stamped envelope, Submarine Delfinul -The XII Biennial Polar Philately, Submarines at the North Pole, 26 Sep` 1998, Bucarest 30th anni` of USS Nautilus, SSN-571, Under the North Pole 3rd August 1958, 3 August 1988, Ploiesti 25th anni` of USS Nautilus, SSN-571, Under the North Pole 3rd August 1958, 3 August 1983, Calarasi