1964 Sc 2884-2886. International year of the quiet Sun. Scott 2839-2841

1964. International year of the quiet Sun.
Catalogs: Scott 2884-2886, Standard Collection 2839-2841, Michel 2862-2864, Yt 2768-2770.
Issued on: 1964-01-01.
Perforation: comb 11½
Printing: Photogravure
Size: 40 x 28 mm, 28 x 40 mm
Colors: Red-lilac, black and orange; brown-orange, dark blue and red; dark blue, dark blue-violet and orange-red.
Face value: 4 Russian kopek; 6 Russian kopek; 10 Russian kopek
Print run: 6,000,000