Gol’bergA. L., and Sevost’yanovE. A. “On the Radius of Injectivity for Generalized Quasiisometries in the Spaces of Dimension Higher Than Two”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 67, no. 2, Feb. 2015, pp. 174-8, https://umj.imath.kiev.ua/index.php/umj/article/view/1972.