V. S. Romanyuk, “Weighted approximation in mean of classes of analytic functions by algebraic polynomials and finite-dimensional subspaces”, Ukr. Mat. Zhurn., vol. 51, no. 5, pp. 645–662, May 1999, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4651