Encinas, Ascensión Hernández Hernández, et al. “Efficient High-Order Finite Difference Methods for Nonlinear Klein–Gordon Equations. I: Variants of the Phi-Four Model and the Form-I of the Nonlinear Klein–Gordon Equation”. Nonlinear Analysis: Modelling and Control, vol. 20, no. 2, Apr. 2015, pp. 274-90, https://doi.org/10.15388/NA.2015.2.9.