I. Aprilo, P. E. Arfanda, M. A. Mappaompo, M. I. Hasanuddin, R. F. Nurulita, and A. Zakaria, “Arm Strength and Shoulder Flexibility in a Physical Training Curriculum: Predictors of Spin Serve Ball Rotation”, IJRER, vol. 5, no. 1, pp. 184–195, Dec. 2025.