صادق أحمد حسن ه. “Definition The Best Tests of the Muscular Endurance from Different Positions for the Males Abdomen Group Muscles in (15-16) Ages”. College of Basic Education Research Journal, vol. 3, no. 1, Jan. 2007, pp. 122-44, https://stats.uomosul.edu.iq/index.php/berj/article/view/39807.