The two oscillator circuits down below are appropriate for using crystal oscillators in sequence or parallel manner: Substantial-repetition-level and large-electric power picosecond regenerative amplifier according to an individual bulk Nd:GdVO4 crystal A timing reference incorporating only one-crystal-silicon micromechanical resonator with a quality element of much larger than a mill... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html