4-pin CMOS oscillators - like the SaRonix NCH060C I’m testing here - contain all the circuitry
necessary to produce an oscillation when voltage is applied.
Internal details are hard to find, but I’m guessing NCH060C is a combination of
crystal resonator with CMOS inverter gate and buffer.
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub