ValeyevK. G., and DzhalladovaI. A. “Derivation of Moment Equations for Solutions of a System of Nonlinear Difference Equations Dependent on a Semi-Markov Process”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 6 (June 25, 2003): 858-864. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3960.