@article{DE_1973_9_7_a20,
     author = {O. A. Kastritsa and G. N. Petrovskiǐ},
     title = {The relative position of the integral tubes of two linear differential systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1347--1348},
     publisher = {mathdoc},
     volume = {9},
     number = {7},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_7_a20/}
}