@article{DE_1977_13_6_a1,
     author = {V. V. Basov},
     title = {Formal and analytic equivalence of real systems of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {981--991},
     publisher = {mathdoc},
     volume = {13},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_6_a1/}
}