@article{DAN_1989_308_1_a7,
     author = {M. M. Lavrent'ev},
     title = {Evolution equations and the {Goursat} problem for a telegraph},
     journal = {Doklady Akademii Nauk},
     pages = {38--41},
     publisher = {mathdoc},
     volume = {308},
     number = {1},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_308_1_a7/}
}