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@article{ARM_1978__14_3_a1, author = {Guggenheimer, H.}, title = {On focal points and limit behavior of solutions of linear differential equations}, journal = {Archivum mathematicum}, pages = {139--143}, publisher = {mathdoc}, volume = {14}, number = {3}, year = {1978}, mrnumber = {0508430}, zbl = {0403.34027}, language = {en}, url = {http://geodesic.mathdoc.fr/item/ARM_1978__14_3_a1/} }
Guggenheimer, H. On focal points and limit behavior of solutions of linear differential equations. Archivum mathematicum, Tome 14 (1978) no. 3, pp. 139-143. http://geodesic.mathdoc.fr/item/ARM_1978__14_3_a1/