I. A. Yurchuk, “Combinatorial aspects of the topological classification of functions on a circle”, Ukr. Mat. Zhurn., vol. 60, no. 6, pp. 829–836, Jun. 2008, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3199