Fushchich, V. I., and V. I. Chopik. “Conditional Symmetry and New Representations of the Galilean Algebra for Nonlinear Parabolic Equations”. Ukrains’kyi Matematychnyi Zhurnal 45, no. 10 (October 25, 1993): 1433–1443. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5948.