Babani, International Radio Tube Encyclopaedia p. 270 & 271
Universal Vade-Mecum, Electron Valves and Semiconductor Devices
Taschenbuch zum Röhren-Codex 1948/49
CV2959: Manufacturer's Literature
Emilio Ciardiello
Just Qvigstad
CV2959: Manufacturer's Literature
Emilio Ciardiello
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