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@article{DE_1975_11_10_a10, author = {A. A. Reinfeld}, title = {The reduction theorem for closed trajectories}, journal = {Differencialʹnye uravneni\^a}, pages = {1811--1818}, publisher = {mathdoc}, volume = {11}, number = {10}, year = {1975}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1975_11_10_a10/} }
A. A. Reinfeld. The reduction theorem for closed trajectories. Differencialʹnye uravneniâ, Tome 11 (1975) no. 10, pp. 1811-1818. http://geodesic.mathdoc.fr/item/DE_1975_11_10_a10/