Maksimenko, S. I., and O. V. Marunkevych. “Topological Stability of the Averagings of Functions”. Ukrains’kyi Matematychnyi Zhurnal, vol. 68, no. 5, May 2016, pp. 625-33, https://umj.imath.kiev.ua/index.php/umj/article/view/1866.