@article{MZ_1967__96_170677,
     author = {Peter J. Lau},
     title = {Stabilit\"atskriterien geschlossener {Charakteristiken} von zweidimensionalen autonomen {Differentialgleichungssystemen.}},
     journal = {Mathematische Zeitschrift},
     pages = {196--213},
     publisher = {mathdoc},
     volume = {96},
     year = {1967},
     zbl = {0166.08801},
     url = {http://geodesic.mathdoc.fr/item/MZ_1967__96_170677/}
}