Al Khalili M., Al Khalili S.M., and Chekalova E.V. “Daniil Medvedev’s Serve and Return Stability Average Percents at Tournaments in the Period of 2019-2023”. Theory and Practice of Physical Culture, no. 11, Nov. 2023, pp. 39-41, http://tpfk.ru/index.php/TPPC/article/view/822.