@article{DAN_1989_309_6_a3,
     author = {V. A. Kozlov},
     title = {The strong zero theorem for an elliptic boundary value problem in},
     journal = {Doklady Akademii Nauk},
     pages = {1299--1301},
     publisher = {mathdoc},
     volume = {309},
     number = {6},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_309_6_a3/}
}