Zagorodnyuk, S. M. “On Series of Orthogonal Polynomials and Systems of Classical Type Polynomials”. Ukrains’kyi Matematychnyi Zhurnal 73, no. 6 (June 18, 2021): 799 - 810. Accessed May 3, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/6527.