KonstantinovA. Yu. “A Class of Admissible Functions in the Principle of Invariance of Wave Operators”. Ukrains’kyi Matematychnyi Zhurnal 46, no. 3 (March 25, 1994): 227–229. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5758.