Several Facts from the History of Russian Electron Valves

Several Facts from the History of Russian Electron Valves.
The "Svetlana" Company based in St. Petersburg and Moskovsky Elektrolampovy Zavod (Moscow Electric-Bulb Plant or MELZ) are the largest manufacturers of electron valves in Russia.
Since the time they were founded at the beginning of the twentieth century the two enterprises have mostly produced electron valves.
"Svetlana" manufactures ...