“The Relationship Between Interval Training Frequency and Aerobic Endurance Level Among Futsal Extracurricular Students at SMPN 3 Ungaran”, Compet. J. Pendidik. Kepelatihan Olahraga, vol. 17, no. 2, pp. 1909–1916, Jun. 2025, doi: 10.26858/cjpko.v17i2.97.