Gadjiev, T. S., and V. A. Mamedova. “On Removable Sets of Solutions of Second-Order Elliptic and Parabolic Equations in Nondivergent Form”. Ukrains’kyi Matematychnyi Zhurnal 61, no. 11 (November 25, 2009): 1485-1496. Accessed April 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3116.