Margiyan, Mochamad Egi, et al. “The Effect of Referee Knowledge, Leadership Style and Confidence on the Performance of Hockey Referee”. Gladi : Jurnal Ilmu Keolahragaan, vol. 13, no. 02, June 2022, pp. 161-77, https://journal.unj.ac.id/unj/index.php/gjik/article/view/23673.