@article{DAN_1969_186_1_a5,
     author = {A. I. Perov},
     title = {New complete solvability conditions and questions of reducibility},
     journal = {Doklady Akademii Nauk},
     pages = {26--29},
     publisher = {mathdoc},
     volume = {186},
     number = {1},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_186_1_a5/}
}