@article{DAN_1968_181_4_a3,
     author = {V. P. Glushko and S. G. Krein},
     title = {Degenerate linear differential equations in a {Banach} space},
     journal = {Doklady Akademii Nauk},
     pages = {784--787},
     publisher = {mathdoc},
     volume = {181},
     number = {4},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_181_4_a3/}
}