@article{DE_1970_6_2_a14,
     author = {A. Kh. Mamyan},
     title = {The construction of solvable extensions in a parallelepiped for linear differential operators with constant coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {358--370},
     publisher = {mathdoc},
     volume = {6},
     number = {2},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_2_a14/}
}