@ARTICLE{8920034,
  author={Dmitriev, Alexander K. and Vershovskii, Anton K.},
  journal={IEEE Sensors Letters}, 
  title={High-Contrast Two-Frequency Optically Detected Resonances in Diamond Nitrogen-Vacancy Centers for Timekeeping Schemes}, 
  year={2020},
  volume={4},
  number={1},
  pages={1-4},
  doi={10.1109/LSENS.2019.2957328}}