@article{MAN_1988__281_4_164407,
     author = {W. Desch and W. Schappacher},
     title = {Some {Perturbation} {Results} for {Analytic} {Semigroups.}},
     journal = {Mathematische Annalen},
     pages = {157--162},
     publisher = {mathdoc},
     volume = {281},
     number = {4},
     year = {1988},
     zbl = {0627.47020},
     url = {http://geodesic.mathdoc.fr/item/MAN_1988__281_4_164407/}
}