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., & Keller, H. U. (1996). Kometen-Zeitzeugen der Entstehung unseres Planetensystems. Nova Acta Leopoldina Suppl., 14, 239-248.