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@article{DAN_1976_229_6_a6, author = {Yu. V. Egorov}, title = {On solvability conditions for differential equations with simple characteristics}, journal = {Doklady Akademii Nauk}, pages = {1310--1312}, publisher = {mathdoc}, volume = {229}, number = {6}, year = {1976}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1976_229_6_a6/} }
Yu. V. Egorov. On solvability conditions for differential equations with simple characteristics. Doklady Akademii Nauk, Tome 229 (1976) no. 6, pp. 1310-1312. http://geodesic.mathdoc.fr/item/DAN_1976_229_6_a6/