REGAL, A.M.; KUMAR, S.D. Non-polynomial spline method for singularly perturbed differential difference equations with delay and advance terms. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 118, n. 2, p. 208–221, 2025. DOI: 10.31489/2025m2/208-221. Disponível em: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/730. Acesso em: 9 jul. 2025.