Julian, Rizki, Agus Kristiyanto, and Sapta Kunta Purnama. “Mental Skill Tennis Referee: Study On Tennis Referee Asian Games And Asian Para Games Indonesia 2018”. Journal of Education, Health and Sport 9, no. 4 (April 2, 2019): 210–219. Accessed April 26, 2025. https://apcz.umk.pl/JEHS/article/view/6777.