1966 Sc 3324. International Hydrological Decade. Scott 3251

1966. International Hydrological Decade.
Catalogs: Scott 3251, Standard Collection 3324, Michel 3275, Yt 3152.
Issued on: 1966-10-12.
Perforation: comb 11½
Printing: Offset lithography
Size: 37 x 37 mm
Colors: Multicolor
Face value: 6 Russian kopek
Print run: 4,000,000