L. A. Masal'tsev, “Harmonic Properties of Gauss Mappings in $H^3$”, Ukr. Mat. Zhurn., vol. 55, no. 4, pp. 489–499, Apr. 2003, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3922