Шульга [Shul’ga A.] О. С., and Саварец [Savarets A.] А. “Characteristics of Non-Olympic Sports Competitions (for Example of the First Category)”. Slobozhanskyi Herald of Science and Sport, no. 5-2(33), Dec. 2012, pp. 54-57, https://journals.uran.ua/index.php/1991-0177/article/view/21596.