AL Khalili, M. ., M. A. . Osaileh, A. . Kuliabin, and O. . Abdelfattah. “Joint Performance Indicators in Tennis”. Dirasat: Educational Sciences, vol. 47, no. 3, Sept. 2020, pp. 442-61, http://dsr.ju.edu.jo/djournals/index.php/Edu/article/view/2431.