@article{DAN_1962_142_1_a4,
     author = {V. A. Il'in},
     title = {The method of {Fourier} for an hyperbolic equation with discontinuous coefficients},
     journal = {Doklady Akademii Nauk},
     pages = {21--24},
     publisher = {mathdoc},
     volume = {142},
     number = {1},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_142_1_a4/}
}