Vinokur, V. V., and V. N. Pavlenko. “Existence Theorems for Equations With Noncoercive Discontinuous Operators”. Ukrains’kyi Matematychnyi Zhurnal, vol. 54, no. 3, Mar. 2002, pp. 349-64, https://umj.imath.kiev.ua/index.php/umj/article/view/4071.