@article{DAN_1960_135_6_a11,
     author = {M. M. Khapaev},
     title = {Asymptotic expansions of the solutions of ordinary linear differential equations in the neighborhood},
     journal = {Doklady Akademii Nauk},
     pages = {1338--1341},
     year = {1960},
     volume = {135},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_135_6_a11/}
}