Novikova, N. ., I. Ivanova, N. . Kotelevskaya, and A. . Golovachev. “Competitive Analysis of Performance of Strongest Junior and Senior Cross-Country Skiers”. Theory and Practice of Physical Culture, no. 3, Apr. 2022, pp. 19-21, http://tpfk.ru/index.php/TPPC/article/view/157.