V. V. Babenko, V. F. Babenko, and M. V. Polishchuk, “Approximation of some classes of set-valued periodic functions by generalized trigonometric polynomials”, Ukr. Mat. Zhurn., vol. 68, no. 4, pp. 449–459, Apr. 2016, Accessed: Apr. 13, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/1851