2 citations to https://www.mathnet.ru/rus/ufa436

1. D. A. Maslov, “About One Method for Numerical Solution of the Cauchy Problem for Singularly Perturbed Differential Equations”, Comput. Math. and Math. Phys., 64:5 (2024), 1029  
2. M. Besova, V. Kachalov, “Axiomatic approach in the analytic theory of singular perturbations”, Axioms, 9:1 (2020), 9