@article{MAN_1980__251_163428,
     author = {W. Hansen},
     title = {Perturbation of {Harmonie} {Spaces.}},
     journal = {Mathematische Annalen},
     pages = {111--122},
     publisher = {mathdoc},
     volume = {251},
     year = {1980},
     zbl = {0421.31009},
     url = {http://geodesic.mathdoc.fr/item/MAN_1980__251_163428/}
}