Mitropolsky , Y. A., Prikarpatsky , A. K., & Samoilenko , V. G. . (1988). Algebraic scheme of discrete approximations of linear and nonlinear dynamic systems of mathematical physics. Ukrains’kyi Matematychnyi Zhurnal, 40(4), 453-458. https://umj.imath.kiev.ua/index.php/umj/article/view/9180