Dorogovtsev , A. Ya., and A. G. Kukush. “Asymptotic Behaviour of the Solution of Cauchy’s Problem for Stochastic Equation of Parabolic Type”. Ukrains’kyi Matematychnyi Zhurnal, vol. 40, no. 2, Feb. 1988, pp. 162-9, https://umj.imath.kiev.ua/index.php/umj/article/view/9112.