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@article{DAN_1957_114_2_a4, author = {N. N. Krasovskii}, title = {On periodical solutions of differential equations involving a time lag}, journal = {Doklady Akademii Nauk}, pages = {252--255}, publisher = {mathdoc}, volume = {114}, number = {2}, year = {1957}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1957_114_2_a4/} }
N. N. Krasovskii. On periodical solutions of differential equations involving a time lag. Doklady Akademii Nauk, Tome 114 (1957) no. 2, pp. 252-255. http://geodesic.mathdoc.fr/item/DAN_1957_114_2_a4/