Mitropolsky Yu. A., BerezovskyA. A., and PlotnitskyT. A. 1992. “Problems With Free Boundaries for the Nonlinear Evolution Equation in Problems of Metallurgy, Medicine, Ecology”. Ukrains’kyi Matematychnyi Zhurnal 44 (1), 67-76. https://umj.imath.kiev.ua/index.php/umj/article/view/7796.