@article{DE_1965_1_7_a1,
     author = {N. I. Shkil'},
     title = {Systems of linear differential equations with a small parameter coefficient of some of the derivatives},
     journal = {Differencialʹnye uravneni\^a},
     pages = {868--879},
     publisher = {mathdoc},
     volume = {1},
     number = {7},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1965_1_7_a1/}
}