@article{DE_1973_9_9_a16,
     author = {V. R. Portnov},
     title = {Normal solvability in the sense of {Hausdorff} of a certain nonlinear problem},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1707--1717},
     publisher = {mathdoc},
     volume = {9},
     number = {9},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_9_a16/}
}