Gavrilyuk, I. P., and V. L. Makarov. “Resonant Equations With Classical Orthogonal Polynomials. II”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 71, no. 4, Apr. 2019, pp. 455-70, https://umj.imath.kiev.ua/index.php/umj/article/view/1451.