@article{RM_1971_26_2_a6,
     author = {Yu. V. Egorov},
     title = {On the solubility of differential equations with simple characteristics},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {113--130},
     publisher = {mathdoc},
     volume = {26},
     number = {2},
     year = {1971},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1971_26_2_a6/}
}