@article{DAN_1975_221_4_a1,
     author = {L. I. Vainerman and M. L. Gorbachuk},
     title = {On boundary value problems for a second-order differential equation of hyperbolic type in a {Hilbert} space},
     journal = {Doklady Akademii Nauk},
     pages = {763--766},
     publisher = {mathdoc},
     volume = {221},
     number = {4},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_221_4_a1/}
}