@article{MAN_1930__103_159417,
     author = {M. Morse},
     title = {A generalization of the {Sturm.} {Separation} und {Comparison} {Theorems} in n-space},
     journal = {Mathematische Annalen},
     pages = {52--69},
     publisher = {mathdoc},
     volume = {103},
     year = {1930},
     zbl = {56.1078.03},
     url = {http://geodesic.mathdoc.fr/item/MAN_1930__103_159417/}
}