Уткіна, Олександра. “Formation of a Specific Biological Cycle in Young Skiers-Racers and Biathletes 11–15 Years, Depending on the Level and Direction of Physical Activity”. Slobozhanskyi Herald of Science and Sport, no. 3(71) (June 30, 2019): 61–66. Accessed August 17, 2024. https://journals.uran.ua/index.php/1991-0177/article/view/171345.