Babani, International Radio Tube Encyclopaedia p. 22 & 23
Universal Vade-Mecum, Electron Valves and Semiconductor Devices Section 106, p. 140
Taschenbuch zum Röhren-Codex 1948/49
41FP: Manufacturer's Literature
Emilio Ciardiello
Just Qvigstad
41FP: Babani Radio Tube Encyclopaedia 1949
Patrice Zeissloff