Babani, International Radio Tube Encyclopaedia p. 50 & 51
Universal Vade-Mecum, Electron Valves and Semiconductor Devices p. 25
Taschenbuch zum Röhren-Codex 1948/49
ARDD1: M.S.
Anónimo 10 Coleccionista
Just Qvigstad
ARDD1: Manufacturer's Literature
Emilio Ciardiello
Mas ...