@article{DE_1980_16_3_a0,
     author = {G. G. Islamov and I. Ya. Shneiberg},
     title = {Existence of nonnegative solutions of linear differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {387--394},
     publisher = {mathdoc},
     volume = {16},
     number = {3},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1980_16_3_a0/}
}