H. A. Dzyubenko, “Pointwise estimation of an almost copositive approximation of continuous functions by algebraic polynomials”, Ukr. Mat. Zhurn., vol. 69, no. 5, pp. 641–649, May 2017, Accessed: Apr. 07, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/1723