@article{DE_1970_6_3_a0,
     author = {E. A. Grebenikov and F. K. Vaskan},
     title = {The reducibility of multifrequency systems of differential equations with summable series},
     journal = {Differencialʹnye uravneni\^a},
     pages = {403--411},
     publisher = {mathdoc},
     volume = {6},
     number = {3},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_3_a0/}
}