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@article{DE_1967_3_5_a14, author = {A. N. Erugin}, title = {Families of extremals}, journal = {Differencialʹnye uravneni\^a}, pages = {849--851}, publisher = {mathdoc}, volume = {3}, number = {5}, year = {1967}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1967_3_5_a14/} }
A. N. Erugin. Families of extremals. Differencialʹnye uravneniâ, Tome 3 (1967) no. 5, pp. 849-851. http://geodesic.mathdoc.fr/item/DE_1967_3_5_a14/