Hung , D. N. X. . “The System of Professional Supplementary Exercises Applied in Teaching Basic Overhand Volleyball Passing Technique for Volleyball-Intensive Students in Danang University of Physical Education and Sports”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 88, no. 1, June 2022, pp. 145-56, https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/7637.