@article{DAN_1986_291_6_a1,
     author = {V. A. Il'in},
     title = {An inequality of {Hilbert} type for a system of eigenfunctions of},
     journal = {Doklady Akademii Nauk},
     pages = {1292--1296},
     publisher = {mathdoc},
     volume = {291},
     number = {6},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1986_291_6_a1/}
}