@article{AM2_1978__18_136801,
     author = {C.S. Hartzman},
     title = {Separatrices and singular points. {(Short} {Communication).}},
     journal = {Aequationes mathematicae},
     pages = {396--398},
     publisher = {mathdoc},
     volume = {18},
     year = {1978},
     url = {http://geodesic.mathdoc.fr/item/AM2_1978__18_136801/}
}