@article{JRAM_1979__305_152082,
     author = {Dieter Erle},
     title = {Stable closed orbits in plane autonomous dynamical systems.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {136--139},
     publisher = {mathdoc},
     volume = {305},
     year = {1979},
     zbl = {0395.34054},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1979__305_152082/}
}