@article{IVM_1990_9_a2,
     author = {Kh. O. Kil'p},
     title = {The differential-geometric structure of a~hyperbolic system of first-order nonlinear equations with two independent variables},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {22--31},
     publisher = {mathdoc},
     number = {9},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1990_9_a2/}
}