AminovY. A. (2019) “On 2-dimensional surfaces in 3-dimensional and 4-dimensional Euclidean spaces. Results and unsolved problems”, Ukrains’kyi Matematychnyi Zhurnal, 71(1), pp. 3-36. Available at: http://umj.imath.kiev.ua/index.php/umj/article/view/1416 (Accessed: 5December2020).