@article{DE_1990_26_1_a7,
     author = {T. Sh. Kal'menov and M. A. Sadybekov},
     title = {The {Dirichlet} problem and nonlocal boundary value problems for the wave equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {60--65},
     publisher = {mathdoc},
     volume = {26},
     number = {1},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_1_a7/}
}