@article{DE_1976_12_12_a13,
     author = {F. E. Lomovtsev and N. J. Yurchuk},
     title = {The {Cauchy} problem for second order hyperbolic operator differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2242--2250},
     publisher = {mathdoc},
     volume = {12},
     number = {12},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_12_a13/}
}