@article{ZNSL_1991_195_a14,
     author = {K. I. Chernyshov},
     title = {Asymptotic expansions of solutions of the linear singularly perturbed differential equations},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {161--178},
     year = {1991},
     volume = {195},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1991_195_a14/}
}