Makarov, V.L. “Higher-Order Differential Equations With Polynomial Solutions Associated With Classical Orthogonal Polynomials”. Reports of the National Academy of Sciences of Ukraine, no. 7 (March 28, 2024): 3–9. Accessed April 18, 2026. https://nasu-periodicals.org.ua/index.php/dp/article/view/2020-7-1.