@article{DE_1990_26_10_a9,
     author = {A. Ya. Lepin},
     title = {Existence of solutions of boundary value problems for a second-order equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1729--1737},
     year = {1990},
     volume = {26},
     number = {10},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_10_a9/}
}