@article{MZM_1977_22_5_a8,
     author = {V. A. Il'in},
     title = {Convergence of eigenfunction expansions at points of discontinuity of the coefficients of a~differential operator},
     journal = {Matemati\v{c}eskie zametki},
     pages = {679--698},
     publisher = {mathdoc},
     volume = {22},
     number = {5},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_22_5_a8/}
}