Urumbaev, A. N. “On the Optimization of Direct Methods for Solving Fredholm Integral Equations of the Second Kind With Infinitely Smooth Kernels”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 12 (December 25, 1993): 1695–1701. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5978.