HentoshО. Ye., and A. K. Prykarpatsky. 2004. “Lie-Algebraic Structure of (2 + 1)-Dimensional Lax-Type Integrable Nonlinear Dynamical Systems”. Ukrains’kyi Matematychnyi Zhurnal 56 (7), 939–946. https://umj.imath.kiev.ua/index.php/umj/article/view/3810.