@article{DAN_1964_159_4_a14,
     author = {A. I. Perov},
     title = {On a higher-dimensional linear differential equation of second order},
     journal = {Doklady Akademii Nauk},
     pages = {755--758},
     publisher = {mathdoc},
     volume = {159},
     number = {4},
     year = {1964},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1964_159_4_a14/}
}