SmolovayaE. S. “Boundary Behavior of Ring <em class="EmphasisTypeItalic ">Q</Em&gt;-Homeomorphisms in Metric Spaces”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 62, no. 5, May 2010, pp. 682–689, https://umj.imath.kiev.ua/index.php/umj/article/view/2898.