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@article{DE_1977_13_6_a22, author = {Yu. A. Pykh}, title = {Differential systems with non-negative normed solutions}, journal = {Differencialʹnye uravneni\^a}, pages = {1138--1140}, publisher = {mathdoc}, volume = {13}, number = {6}, year = {1977}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1977_13_6_a22/} }
Yu. A. Pykh. Differential systems with non-negative normed solutions. Differencialʹnye uravneniâ, Tome 13 (1977) no. 6, pp. 1138-1140. http://geodesic.mathdoc.fr/item/DE_1977_13_6_a22/