Chakravarthy, P. P., T. Gupta, and N. R. Rao. “A Numerical Scheme for Singularly Perturbed Delay Differential Equations of Convection-Diffusion Type on an Adaptive Grid”. Mathematical Modelling and Analysis, Vol. 23, no. 4, Oct. 2018, pp. 686-98, doi:10.3846/mma.2018.041.