@article{DAN_1975_225_1_a6,
     author = {A. V. Bitsadze},
     title = {The influence of the minor terms on the correctness of the formulation of characteristic problems for hyperbolic systems of second order},
     journal = {Doklady Akademii Nauk},
     pages = {31--34},
     publisher = {mathdoc},
     volume = {225},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_225_1_a6/}
}