Awras Naima Hassan, and Mohammed Matar Al-Ajili. “Evaluation of the Accuracy of the Spike Shot for Al-Muthanna University Volleyball Team Players Based on the Indicators of (Ball Speed and Variable Error of Distance)”. Modern Sport, vol. 18, no. 2, June 2019, pp. 429-38, https://www.jcopew.uobaghdad.edu.iq/index.php/sport/article/view/1577.