Team, S. “Convergence of the Variational Iteration Method for Solving a First-Order Linear System of PDEs With Constant Coeffcients: Momtri Torvattanabun, Sanoe Koonprasert”. Thai Journal of Mathematics, vol. 7, no. 3, Dec. 2009, pp. 1-13, https://thaijmath2.in.cmu.ac.th/index.php/thaijmath/article/view/173.