@article{JRAM_1974__267_151437,
     author = {Ekkehard Wagenf\"uhrer},
     title = {\"Uber regul\"ar-singul\"are {L\"osungen} von {Systemen} linearer {Differentialgleichungen.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {90--114},
     publisher = {mathdoc},
     volume = {267},
     year = {1974},
     zbl = {0287.34007},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1974__267_151437/}
}