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@article{DE_1975_11_4_a18, author = {E. I. Zheleznov}, title = {Necessary optimality conditions for singular extremals}, journal = {Differencialʹnye uravneni\^a}, pages = {749--752}, publisher = {mathdoc}, volume = {11}, number = {4}, year = {1975}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1975_11_4_a18/} }
E. I. Zheleznov. Necessary optimality conditions for singular extremals. Differencialʹnye uravneniâ, Tome 11 (1975) no. 4, pp. 749-752. http://geodesic.mathdoc.fr/item/DE_1975_11_4_a18/