Vyhovs’kaI. Yu., and ZelinskiiYu. B. “Criterion for Convexity of a Domain of a Euclidean Space”. Ukrains’kyi Matematychnyi Zhurnal 60, no. 5 (May 25, 2008): 709–711. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3189.