@article{DE_1971_7_5_a8,
     author = {Sh. A. Alimov and V. A. Il'in},
     title = {Conditions for the convergence of spectral decompositions that correspond to self-adjoint extensions of elliptic operators. {II.} {Self-adjoint} extension of the {Laplace} operator with an arbitrary spectrum},
     journal = {Differencialʹnye uravneni\^a},
     pages = {851--882},
     publisher = {mathdoc},
     volume = {7},
     number = {5},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1971_7_5_a8/}
}