Five airmail covers sent to Estonia, when it was still part of the Soviet Union (Russia) between 1973 and early 1976. The condition is fine for the majority, rather than VF, but any mail to the Soviet Union at this time is scarce, and the covers all have Russian backstamps. Three are overpaid by 1c, one is sent at the correct 15c rate and one is sent at the 20c rate which was in effect in 1976.
