@article{DAN_1970_191_6_a7,
     author = {Ya. A. Roitberg},
     title = {A homeomorphism theorem for general elliptic boundary value problems with boundary conditions that are not the normal ones},
     journal = {Doklady Akademii Nauk},
     pages = {1228--1231},
     publisher = {mathdoc},
     volume = {191},
     number = {6},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_191_6_a7/}
}