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@article{DE_2005_41_8_a14, author = {Yu. S. Kolesov}, title = {Proof of {Levin's} {Half-Period} {Theorem}}, journal = {Differencialʹnye uravneni\^a}, pages = {1125--1127}, publisher = {mathdoc}, volume = {41}, number = {8}, year = {2005}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_2005_41_8_a14/} }
Yu. S. Kolesov. Proof of Levin's Half-Period Theorem. Differencialʹnye uravneniâ, Tome 41 (2005) no. 8, pp. 1125-1127. http://geodesic.mathdoc.fr/item/DE_2005_41_8_a14/