@article{MZM_1981_29_6_a7,
     author = {M. O. Otelbaev},
     title = {A criterion for the coincidence of extensions, corresponding to {Dirichlet's} and {Neumann's} problems, of an elliptic operator},
     journal = {Matemati\v{c}eskie zametki},
     pages = {867--875},
     publisher = {mathdoc},
     volume = {29},
     number = {6},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1981_29_6_a7/}
}