@article{RM_1962_17_1_a19,
     author = {A. B. Shabat},
     title = {Boundary-value problems with small parameter for ordinary linear differential equations},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {17},
     number = {1},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1962_17_1_a19/}
}