Filshtinskiy, Vadim A., and Leonid A. Filshtinskiy. “About One Approach to Approximate Solutions of Functional Equations”. Ecological Bulletin of Research Centers of the Black Sea Economic Cooperation, no. 1 (March 30, 2004): 10–17. Accessed December 6, 2025. https://vestnik.kubsu.ru/article/view/19.