USSR
Acknowledged, but not listed by SG.
| Country: | USSR |
| Type: | Postal blocks |
| Series: | 20th Anniversary of First Manned Space Flight |
| Nominal: | 6*6 k |
| Year: | 1981 |
| Material: | coated |
| Perforation: | comb 11½ x 12 |
| Mintage: | 12,500 |
20th Anniversary of First Manned Space Flight
 Cosmonautics Day, 1981 - Yuri Gagarin |  Cosmonautics Day, 1981 - Sergei Korolev |  Cosmonautics Day, 1981 - Monument "To the Stars" |  Cosmonautics Day, 1981 - Sculpture of Yuri Gagarin, 1967 2.3$ |