Harmonic analysis and Radon transforms on pencils of geodesics. E. Badertscher — 1986 Mathematica Scandinavica
An explicit formula about the convex hull of random points. E. Badertscher — 1989 Elemente der Mathematik
Harmonic Analysis for Vector Fields on Hyperbolic Spaces. H.M. Reimann; E. Badertscher — 1989 Mathematische Zeitschrift