@article{DAN_1962_146_4_a9,
     author = {P. E. Sobolevskii},
     title = {On second-order differential equations in a {Banach} space},
     journal = {Doklady Akademii Nauk},
     pages = {774--777},
     publisher = {mathdoc},
     volume = {146},
     number = {4},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_146_4_a9/}
}