Crystals over 30 MHz (around >200 MHz) are typically operated at collection resonance where by the impedance seems at its minimum amount and equal to the collection resistance. For these crystals the collection resistance is specified ( SMD crystals consist of really little phase noise, which leads to little jitter https://setbookmarks.com/story19040712/helping-the-others-realize-the-advantages-of-smd-crystal-oscillators