SalimovR. R. “On the Boundary Behavior of Imbeddings of Metric Spaces into a Euclidean Space”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, no. 8, Aug. 2007, pp. 1068–1074, https://umj.imath.kiev.ua/index.php/umj/article/view/3370.