Dr.Hashim Shakir Abdulkareem, Dr. Abdullah Shanta Faraj, Dr. Imad Faraj Badrawi, and Dr. Hussam mohamid jabber, “THE EFFECT OF FARTLEK TRAINING ON SPECIAL ENDURANCE AND DIGITAL ACHIEVEMENT OF EFFECTIVENESS 4 X 400 RELAY”, Euro. J. Hum. Edu. Adv., vol. 3, no. 10, pp. 144-148, Oct. 2022.