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@article{DE_1987_23_5_a22, author = {V. N. Gorbuzov and {\CYRS}. {\CYRI}. Kishkel}, title = {Apropos a theorem of {Wittich}}, journal = {Differencialʹnye uravneni\^a}, pages = {891--893}, publisher = {mathdoc}, volume = {23}, number = {5}, year = {1987}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1987_23_5_a22/} }
V. N. Gorbuzov; С. И. Kishkel. Apropos a theorem of Wittich. Differencialʹnye uravneniâ, Tome 23 (1987) no. 5, pp. 891-893. http://geodesic.mathdoc.fr/item/DE_1987_23_5_a22/