@article{DE_1977_13_4_a6,
     author = {V. I. Bernik and B. I. Ptashnic and B. O. Salyga},
     title = {An analogue of the multipoint problem for a hyperbolic equation with constant coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {637--645},
     publisher = {mathdoc},
     volume = {13},
     number = {4},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_4_a6/}
}