Gniezińska, Anna, and Karol Bar. “The Analysis of Sports Results Obtained by Pupils in Primary Schools Championships in Katowice in Swimming in the Years 2012 – 2016”. Journal of Education, Health and Sport, vol. 8, no. 11, Nov. 2018, pp. 328-36, https://apcz.umk.pl/JEHS/article/view/6304.