@article{DAN_1981_257_5_a10,
     author = {S. Ya. Yakubov and B. A. Aliev},
     title = {The {Fredholm} property of a boundary value problem, with an operator in the boundary conditions, for an elliptic differential operator equation of second order},
     journal = {Doklady Akademii Nauk},
     pages = {1071--1074},
     publisher = {mathdoc},
     volume = {257},
     number = {5},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_257_5_a10/}
}