Sevost’yanovE. A. “Removal of Singularities and Analogs of the Sokhotskii–Weierstrass Theorem for Q-Mappings”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 61, no. 1, Jan. 2009, pp. 116-2, https://umj.imath.kiev.ua/index.php/umj/article/view/3007.