@article{MAN_1963__151_161070,
     author = {J.J. Sch\"affer},
     title = {Linear {Differential} {Equations} and {Functional} {Analysis,} {VIII.}},
     journal = {Mathematische Annalen},
     pages = {57--100},
     publisher = {mathdoc},
     volume = {151},
     year = {1963},
     zbl = {0115.10804},
     url = {http://geodesic.mathdoc.fr/item/MAN_1963__151_161070/}
}