Ali Hameed Ali Al-Zubaidi. “The Effect of Using Fartlek Training Method on Developing Speed, Strength Endurance, and Court Defense Skill Performance in Volleyball”. Jurnal Nakula : Pusat Ilmu Pendidikan, Bahasa dan Ilmu Sosial 3, no. 3 (May 15, 2025): 329–337. Accessed May 16, 2025. https://journal.aripi.or.id/index.php/Nakula/article/view/1837.