@article{DAN_1957_116_6_a1,
     author = {N. N. Vakhania},
     title = {A boundary problem for a hyperbolic system equivalent to the string vibration equation},
     journal = {Doklady Akademii Nauk},
     pages = {906--909},
     publisher = {mathdoc},
     volume = {116},
     number = {6},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_116_6_a1/}
}