Kovalenko, S. S. “Symmetry Analysis and Exact Solutions of One Class of (1 + 3)-Dimensional Boundary-Value Problems of the Stefan Type”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 63, no. 10, Oct. 2011, pp. 1352-9, https://umj.imath.kiev.ua/index.php/umj/article/view/2811.