Popov, G. Ya. “On Some Integral Transformations and Their Application to the Solution of Boundary-Value Problems in Mathematical Physics”.
Ukrains’kyi Matematychnyi Zhurnal 53, no. 6 (June 25, 2001): 810–819. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/4301.