Keller, H. U. Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society; MPI for Aeronomy, Max Planck Institute for Solar System Research, Max Planck Society;
Kührt, E., Knollenberg, J., & Keller, H. U. (1997). Physical risks of landing on a cometary nucleus. Planetary and Space Science, 45, 665-680.