Oktavia, N., N. Denay, and D. P. Sari. “The Effect of Rubber Training on Gyaku-Tsuki Punching Speed in Karate Athletes”. International Martial Arts and Culture Journal, vol. 1, no. 2, Dec. 2023, pp. 64-67, https://imacj.ppj.unp.ac.id/index.php/imacj/article/view/10.