@article{MMO_1974_31_a1,
     author = {O. A. Oleǐnik and E. V. Radkevi\v{c}},
     title = {Conditions for the existence of nonanalytic solutions of linear partial differential equations of arbitrary order},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {17--33},
     publisher = {mathdoc},
     volume = {31},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1974_31_a1/}
}