DegtyarevS. P. “Influence of the Inhomogeneity of Porous Media on the Instantaneous Compactification of the Support of Solution of the Filtration Problem”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, no. 8, Aug. 2006, pp. 1035–1044, https://umj.imath.kiev.ua/index.php/umj/article/view/3512.