@article{SM_1968_4_3_a9,
     author = {B. R. Vainberg},
     title = {On elliptic problems in unbounded domains},
     journal = {Sbornik. Mathematics},
     pages = {419--444},
     year = {1968},
     volume = {4},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1968_4_3_a9/}
}