@article{DE_1991_27_2_a18,
     author = {V. A. Baltag},
     title = {Cubic null-systems of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {345--347},
     publisher = {mathdoc},
     volume = {27},
     number = {2},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_2_a18/}
}