StegantsevaP., and GrechnevaM. “Two-Dimensional Nonisotropic Surfaces With Flat Normal Connection and a Nondegenerate Grassmann Image of Constant Curvature in the Minkowski Space”. Ukrains’kyi Matematychnyi Zhurnal 76, no. 4 (April 26, 2024): 533 - 551. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/6743.