Петренко [Sergiy Petrenko] С. І. “Physical Capacity and Functional Resources of the Respiratory System of Young Footballers With Various Biological Development”. Slobozhanskyi Herald of Science and Sport, no. 2(35), Apr. 2013, pp. 120-3, https://journals.uran.ua/index.php/1991-0177/article/view/18483.