Y. A. Aminov, “On 2-dimensional surfaces in 3-dimensional and 4-dimensional Euclidean spaces. Results and unsolved problems”, Ukr. Mat. Zhurn., vol. 71, no. 1, pp. 3–36, Jan. 2019, Accessed: Apr. 13, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/1416