Noreddin , M. M., and N. Ya. Tikhonenko. “On Convergence of the Method of Orthogonal Polynomials of the Approximate Solution оf the Second Order Integral Equations With $\Pi$-Kernels”. Ukrains’kyi Matematychnyi Zhurnal, vol. 43, no. 2, June 2025, pp. 223-9, https://umj.imath.kiev.ua/index.php/umj/article/view/9361.