Nurrahman, T., Aluwis, A., & Prawibowo, M. (2026). Analysis of Underhand Serve Ability in Volleyball Game Among Extra-Curricular Students at Bahrul Ulum Islamic Boarding School, Pasir Utama, Rokan Hulu Regency. Jurnal Ilmu Keolahragaan, 1(2), 19-27. https://doi.org/10.65943/jikor.2026.v1.i2.69