@article{UFA_2016_8_3_a11,
     author = {E. A. Sozontova},
     title = {On solvability by quadratures conditions for second order hyperbolic systems},
     journal = {Ufa mathematical journal},
     pages = {130--135},
     publisher = {mathdoc},
     volume = {8},
     number = {3},
     year = {2016},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/UFA_2016_8_3_a11/}
}