Репета, В.К., and Л.А. Репета. “The Approximation of the Functions from the Classes by Steklov’s Operators”. Proceedings of National Aviation University (archive) 22, no. 4 (April 1, 2004): 171–175. Accessed June 14, 2026. http://jrnl.kai.edu.ua/index.php/visnik/article/view/1084.