Mahmuddin, M., R. S. D. Sihombing, S. Yunis Bangun, and D. Josua Hamonangan. “The Effect of Exercise Variation Methods on Leg Muscle Strength and Its Contribution to Improving Volleyball Smash Results”. Jurnal SPORTIF : Jurnal Penelitian Pembelajaran, Vol. 10, no. 1, Apr. 2024, pp. 126-38, doi:10.29407/js_unpgri.v10i1.22242.