Dubins' problem is intrinsically three-dimensional Dirk Mittenhuber — 1998 ESAIM: Control, Optimisation and Calculus of Variations
On the causal structure of Lorentzian Lie groups. A globality theorem for Lorentzian cones in certain solvable Lie algebras. Dirk Mittenhuber — 1996 Mathematische Annalen
On the exponential function of an ordered manifold with affine connection. Dirk Mittenhuber; Karl-Herrmann Neeb — 1995 Mathematische Zeitschrift