@article{DE_1965_1_4_a2,
     author = {N. N. Vinogradov},
     title = {Certain existence theorems for a periodic solution and theorems on determining the boundary of a region of asymptotic stability of the trivial solution of a system of ordinary differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {442--448},
     publisher = {mathdoc},
     volume = {1},
     number = {4},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1965_1_4_a2/}
}