Crystal oscillator with a 6A6 (T437E)

We found this circuit with the 6A6 double triode in a 1938 Radio Handbook. The power source is not provided.

Infrared Transmitter (CB20337E)
This infrared emitter (pulsating) can be used with several other alarm and remote-control circuits on...
UJT Triangular Signal Generator (CB19509E)
Signals of up to a few tens of kilohertz can be generated by this circuit found in a European...
Broadband Amplifier (CB20057E)
This amplifier was found in a technical documentation from the 1970s. The circuit uses 2N2218...