@article{BUMI_1964_3_19_4_a5,
     author = {Coppel, W. A.},
     title = {On the uniqueness of limit cycles.},
     journal = {Bollettino della Unione matematica italiana},
     pages = {441--445},
     publisher = {mathdoc},
     volume = {Ser. 3, 19},
     number = {4},
     year = {1964},
     zbl = {0128.31402},
     mrnumber = {177164},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BUMI_1964_3_19_4_a5/}
}