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@article{DE_1977_13_6_a3, author = {I. T. Kiguradze}, title = {The periodic boundary value problem for a two-dimensional differential system}, journal = {Differencialʹnye uravneni\^a}, pages = {996--1007}, publisher = {mathdoc}, volume = {13}, number = {6}, year = {1977}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1977_13_6_a3/} }
I. T. Kiguradze. The periodic boundary value problem for a two-dimensional differential system. Differencialʹnye uravneniâ, Tome 13 (1977) no. 6, pp. 996-1007. http://geodesic.mathdoc.fr/item/DE_1977_13_6_a3/