VakarchukS. B., & ShvachkoA. V. (2013). On the Best Approximation in the Mean by Algebraic Polynomials with Weight and the Exact Values of Widths for the Classes of Functions. Ukrains’kyi Matematychnyi Zhurnal, 65(12), 1604–1621. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/2540