@article{IVM_1982_12_a15,
     author = {Kh. G. Umarov},
     title = {Solution by {Riemann's} method of the {Goursat} problem for certain hyperbolic equations with variable operator coefficients},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {76--79},
     publisher = {mathdoc},
     number = {12},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1982_12_a15/}
}