R. Hisham and W. Gassem, “The effect of skill exercises (individual - collective) according to the type of learning (contemplative - practical) in learning some of the basic skills of volleyball for students of the fifth preparatory”, jope, vol. 31, no. 2, pp. 188–204, Jun. 2019, doi: 10.37359/JOPE.V31(2)2019.933.