Kapustyan, O. V., and P. O. Kasyanov. “Global Attractor for a Nonautonomous Inclusion With Discontinuous Right-Hand Side”. Ukrains’kyi Matematychnyi Zhurnal, vol. 55, no. 11, Nov. 2003, pp. 1467-75, https://umj.imath.kiev.ua/index.php/umj/article/view/4017.