salim, ahmed, S. Kadum, and M. Khaleel. “Fartlek Exercises and Their Effect on Molecular Biology (vascular Endothelial Growth Factor-Basic Fibroblast Growth Factor) and Some Physical Variables for Players 800m Arena and Field for Youth”. Al-Rafidain Journal For Sport Sciences, vol. 25, no. 77, Aug. 2022, pp. 127-42, doi:10.33899/rjss.2022.175434.