Grigoryan, A.L. (2004) “Estimate of the Remainder of the Best Quadratic Approximation of Differentiable Functions by Polynomials”, Ukrains’kyi Matematychnyi Zhurnal, 56(12), pp. 1691–1698. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3876 (Accessed: 5 December 2025).