BonafedeS. “Strongly Nonlinear Degenerate Elliptic Equations With Discontinuous Coefficients. II”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 49, no. 12, Dec. 1997, pp. 1601–1609, https://umj.imath.kiev.ua/index.php/umj/article/view/5164.