@article{RM_1960_15_4_a1,
     author = {M. I. Vishik and L. A. Lyusternik},
     title = {The asymptotic behaviour of solutions of linear differential equations with large or quickly changing coefficients and boundary conditions},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {23--91},
     publisher = {mathdoc},
     volume = {15},
     number = {4},
     year = {1960},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1960_15_4_a1/}
}