@article{DAN_1960_132_5_a3,
     author = {G. V. Virabyan},
     title = {The spectrum of a certain operator and {Dirichlet's} problem for the equation},
     journal = {Doklady Akademii Nauk},
     pages = {986--989},
     year = {1960},
     volume = {132},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_132_5_a3/}
}