@article{DE_1978_14_11_a26,
     author = {L. F. Yanchuk},
     title = {The asymptotic equivalence of {Pfaffian} systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2099--2103},
     publisher = {mathdoc},
     volume = {14},
     number = {11},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_11_a26/}
}