Try searching the Heratige auction archives. www.HA.com It's free to sign up and search. Brad www.lincolncentresource.com
Overstrikes are VERY fascinating, but at times in the case of old Russian coins, you can get DOUBLE overstrikes with three different denominations, although I have yet to see a triple overstrike. 1759 2kopeks over 1755 MMD 1 kopek over 1727 5 kopeks