@article{DAN_1967_175_6_a4,
     author = {I. M. Lavrent'ev},
     title = {Solvability of nonlinear equations},
     journal = {Doklady Akademii Nauk},
     pages = {1219--1221},
     publisher = {mathdoc},
     volume = {175},
     number = {6},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_175_6_a4/}
}