Tamala, Aprilia Putri, et al. “Enhancing Gross Motor Skills through Competition-Based Obstacle Play: An Effectiveness Study at TK Khadijah Surabaya”. Nak-Kanak: Journal of Child Research, vol. 2, no. 4, Nov. 2025, pp. 145-57, doi:10.21107/njcr.v2i4.182.