@article{DAN_1967_177_1_a5,
     author = {V. A. Il'in},
     title = {On fundamental function systems of {Laplace's} operator in an arbitrary region and on asymptotic estimates of the fundamental numbers},
     journal = {Doklady Akademii Nauk},
     pages = {25--28},
     publisher = {mathdoc},
     volume = {177},
     number = {1},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_177_1_a5/}
}