Luna 16 and Luna 17/Lunokhod 1
The flights of Luna 16 (first automatic retrieval of Moon samples) and Luna 17 (first robotic Moon rover) were a popular subject for stamp designers. This pair from Romania was issued joined together (se-tenant, as the philatelists say). The left-hand stamp shows the Luna 16 upper stage taking off from the Moon carrying lunar samples back to Earth, while the other shows the Lunokhod 1 Moon rover leaving tracks in the soil as it drives away from the Luna 17 landing stage.
Stanley Gibbons catalogue numbers:
The stamps were also issued in a commemorative sheet of four with descriptive labels, below.
This sheet has no SG number.