Pramono, H., T. Rahayu, and D. Yudhistira. “The Effect of Plyometrics Exercise through Agility Ladder Drill on Improving Physical Abilities of 13–15-Year-Old Volleyball Players”. Physical Education Theory and Methodology, vol. 23, no. 2, Apr. 2023, pp. 199-06, doi:10.17309/tmfv.2023.2.07.