@article{DE_1987_23_3_a6,
     author = {B. S. Kalitin},
     title = {On a comparison method for a problem of stability of periodic systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {423--428},
     publisher = {mathdoc},
     volume = {23},
     number = {3},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_3_a6/}
}