Akhmad, Imran, et al. “Speed, Agility, and Quickness (SAQ) Training of the Circuit System: How Does It Affect Kick Speed and Agility of Junior Taekwondo Athletes? ”. Journal Sport Area, vol. 6, no. 2, July 2021, pp. 175-82, doi:10.25299/sportarea.2021.vol6(2).6433.