@article{DE_1990_26_12_a0,
     author = {I. E. Vitrichenko},
     title = {On the stability in the critical case of a zero root and of a pair of purely imaginary roots of a nonautonomous $n$th order quasilinear equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2027--2046},
     publisher = {mathdoc},
     volume = {26},
     number = {12},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_12_a0/}
}