Sato, B., R. Wakatsuki, Y. Kashiwagi, and K. Funato. “Ball Velocity and Spin at the Impact of Tennis Serves: Reliability of a Ball Motion Measurement Instrument (TRACKMAN)”. ITF Coaching & Sport Science Review, vol. 25, no. 73, Dec. 2017, pp. 35-38, doi:10.52383/itfcoaching.v25i73.305.