@article{DE_1989_25_4_a12,
     author = {S. E. Zhelezovsky and V. Ph. Kirichenko and V. A. Krys'ko},
     title = {Symmetrization of a hyperbolic equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {652--659},
     publisher = {mathdoc},
     volume = {25},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_4_a12/}
}