Analysis of the Photoelectric State by Georgi Nadjakov 3 лв — Bulgaria, 1994
Analysis of the Photoelectric State by Georgi Nadjakov (Bulgaria, 1994), face value 3 лв, “Europa (C.E.P.T.) 1994 - Discoveries and Inventions” series…
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Europa (C.E.P.T.) 1994 - Discoveries and Inventions