Shishkin, G. I. “Robust Novel high‐order Accurate Numerical Methods for Singularly Perturbed convection‐diffusion Problems”. Mathematical Modelling and Analysis 10, no. 4 (December 31, 2005): 393-412. Accessed February 6, 2025. https://transport.vgtu.lt/index.php/MMA/article/view/9694.