Stamped USSR post card dedicated to 12th International Botanical Congress - Colloquia Botanicorum (Leningrad, 1975) with a preprinted (original) stamp, 1975, 4 kop.
USSR government
Personal collection. Scanned and processed by <a href="//commons.wikimedia.org/wiki/User:Leonid_Dzhepko" title="User:Leonid Dzhepko">Leonid Dzhepko</a> \ own scan \ свой скан маркированной почтовой карточки - <b>официального знака почтовой оплаты</b>