Inaam Abdul-ridha Ali, Suhad Qassim Al-Musawi, Abeer Dakhil Hatem. Effect of using flat hierarchical method on some aspects of muscular strength and straight serve skill for nascent tennis players. ms [Internet]. 2020 Jun. 30 [cited 2024 Dec. 19];19(2):0008. Available from: https://jcopew.uobaghdad.edu.iq/index.php/sport/article/view/537