SidenkoN. R. “$G$-Convergence of Periodic Parabolic Operators With a Small Parameter by the Time Derivative”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 45, no. 4, Apr. 1993, pp. 525–538, https://umj.imath.kiev.ua/index.php/umj/article/view/5840.