This circuit, from a component manual, also applies to other components in the same family. The font does not have to be symmetrical, and the characteristics are given next to the diagram.
Using an operational that is not common today, but which admits a modern equivalent, we found this...
This simple source of up to 1 A can supply voltages according to the secondary of the transformer, in this...
This interference rejection circuit for telegraphy was found in a 1980s documentation for radio...