@article{RM_1973_28_3_a19,
     author = {O. A. Oleinik and E. V. Radkevich},
     title = {A certain class of linear differential equations that have nonanalytic solutions},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     year = {1973},
     volume = {28},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1973_28_3_a19/}
}