Firsov, D. “Stability of Explicit Schemes for Solving Maxwell’s Equations by High-Order Finite Volume Methods”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie), vol. 15, no. 40, May 2014, pp. 286-03, https://en.num-meth.ru/index.php/journal/article/view/768.