@article{MAN_1979__240_163224,
     author = {Hans Christoph Im Hof},
     title = {The {Family} of {Horospheres} {Through} {Two} {Points.}},
     journal = {Mathematische Annalen},
     pages = {1--12},
     publisher = {mathdoc},
     volume = {240},
     year = {1979},
     zbl = {0379.53020},
     url = {http://geodesic.mathdoc.fr/item/MAN_1979__240_163224/}
}