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They definitely look like some stamps.
Pictures are of famous polish paintings, there may be a year printed somewhere on the stamps if you look closely.
here is the complete serie on [stampworld.com](https://stampworld.com) https://www.stampworld.com/stamps/Poland/Postage-stamps/g1936//
Stamps from 1969 https://www.lastdodo.nl/nl/areas/152975-polen?cf%5B7849%5D=116457&page=3 You can find them here and buy the rest of the series, 1 cent each.
polish modern stamps on art.
They definitely look like some stamps.
Pictures are of famous polish paintings, there may be a year printed somewhere on the stamps if you look closely.
here is the complete serie on [stampworld.com](https://stampworld.com) https://www.stampworld.com/stamps/Poland/Postage-stamps/g1936//
Stamps from 1969 https://www.lastdodo.nl/nl/areas/152975-polen?cf%5B7849%5D=116457&page=3 You can find them here and buy the rest of the series, 1 cent each.
polish modern stamps on art.