UrumbaevA. N. “On Finite-Dimensional Approximation of Solutions of Ill-Posed Problems”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 2 (February 25, 1997): 289–295. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5005.