@article{MZ_1966__91_170501,
     author = {G\"unter Ewald and Geoffrey C. Shephard},
     title = {Normed vector spaces consisting of classes of convex sets.},
     journal = {Mathematische Zeitschrift},
     pages = {1--19},
     publisher = {mathdoc},
     volume = {91},
     year = {1966},
     zbl = {0141.39003},
     url = {http://geodesic.mathdoc.fr/item/MZ_1966__91_170501/}
}