Purnomo, Ardhi Mardiyanto Indra, et al. “Effects of Different Squat Angles and Surface Stability on Lower Limb Muscle Activation: A Surface Electromyography Study”. Journal Sport Area, vol. 11, no. 1, Apr. 2026, pp. 116-2, doi:10.25299/sportarea.2026.vol11(1).25271.