Valeyev, K. G., and I. A. Dzhalladova. 2004. “Second-Order Moment Equations for a System of Differential Equations With Random Right-Hand Side”. Ukrains’kyi Matematychnyi Zhurnal 56 (5), 687-91. https://umj.imath.kiev.ua/index.php/umj/article/view/3788.