@article{PORMA_1976__35_4_115290,
     author = {Herold, Horst},
     title = {Vergleichss\"atze f\"ur {Komplexe} {Lineare} {Differentialgleichungen} 2. {Ordnung}},
     journal = {Portugaliae mathematica},
     pages = {213--219},
     year = {1976},
     volume = {35},
     number = {4},
     zbl = {0394.34013},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1976__35_4_115290/}
}