Agustiyanto, Agustiyanto. “Effect of Boteli and Frequency Modification Exercise in Improving Groundstroke Forehand Really Skills in Tennis ”. Jurnal SPORTIF : Jurnal Penelitian Pembelajaran 9, no. 2 (August 16, 2023): 274-289. Accessed July 8, 2024. https://ojs.unpkediri.ac.id/index.php/pjk/article/view/19953.