Stojanović, M. “Adaptive Spline Difference Scheme for Singular Perturbation Problem With Mixed Boundary Conditions”.
Anal. Numér. Théor. Approx. 18, no. 2 (August 1, 1989): 171–181. Accessed April 11, 2025.
https://ictp.acad.ro/jnaat/journal/article/view/1989-vol18-no2-art8.