A. L. . Golberg, “On certain classes of plane topological representations with the first generalized derivatives”, Ukr. Mat. Zhurn., vol. 44, no. 8, pp. 1114–1116, Sep. 1992, Accessed: Apr. 16, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8043