Thank you Rick.
1) Notice that on 1965 Steiner Page 48. the Forest Animal set, there is no indication of what the animals are. This is not the only Polish set with this characteristic.
Interesting, I think I know them all (Including the European Bison)
but for the kids taking up the hobby........
I also find it surprising that stamp producers still overprint their issues sometimes in Silver, what a waste of time and effort.
Try and find the Polish Opts on the 1963 Space program, virtually impossible to spot.
Steiner Page 46.
Steiner Page 47.
Personal Page 47B