Друзь [Valeriy Druz] В.А., Жерновнікова [Yana Zhernovnicova] Я. and Пятисоцька [Svitlana Pyatisotskaya] С.С. 2013. Main criteria of estimation of the physical development and biological age of junior school-children which determine individual approach in the process of physical education. Slobozhanskyi Herald of Science and Sport. 3(36) (Jun. 2013), 81–85.