V. Ruka, C. Kungku, D. Purwanto, and N. Sukrawan, “The Effect of Hurdle Hopping and Burpees Exercises on Vertical Jump Ability in Volleyball Games of Extracurricular Students at SMPN 6 Palu”, IJoASER, vol. 9, no. 2, pp. 272-279, Aug. 2026.