@article{DE_1969_5_3_a13,
     author = {V. G. Raskin and P. E. Sobolevskii},
     title = {Expansion of the solutions of second order differential equations in {Banach} spaces in series of exponential solutions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {543--545},
     publisher = {mathdoc},
     volume = {5},
     number = {3},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_3_a13/}
}