Komarudin, Sandey Tantra Paramitha, Muhammad Gilang Ramadhan, and Geraldi Novian. “Increasing Mental Toughness through COVID-19 Gymnastics in Adult People”. Journal Sport Area 7, no. 3 (December 5, 2022): 354–360. Accessed May 7, 2024. https://journal.uir.ac.id/index.php/JSP/article/view/9080.