AzizovM. 1996. “On the Optimal Rate of Convergence of the Projection-Iterative Method and Some Generalizations of It on a Class of Equations With Smoothing Operators”. Ukrains’kyi Matematychnyi Zhurnal 48 (11), 1448-56. https://umj.imath.kiev.ua/index.php/umj/article/view/5198.