Crystal oscillators are loosely divided from the frequency they work at and whether they are elementary oscillators—function with the frequency marked within the can or at even multiples of that (overtone oscillators). Modeling of nonlinear micromechanical resonators and their simulation Using the harmonic‐equilibrium approach HTML White paper TI BAW engineering https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html