@article{DE_1993_29_5_a23,
     author = {V. G. Romanovsky},
     title = {On the calculation of {Lyapunov} quantities in the case of two purely imaginary roots},
     journal = {Differencialʹnye uravneni\^a},
     pages = {910--912},
     publisher = {mathdoc},
     volume = {29},
     number = {5},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1993_29_5_a23/}
}