Mel’nikV. L. “Investigation of Smoothness Conditions on the Boundary for the Strong Linear Convexity of a Domain”. Ukrains’kyi Matematychnyi Zhurnal 51, no. 12 (December 25, 1999): 1710–1713. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4774.