He was professor at the University of Cologne 1980-1983 and holds the Chair of Mediaeval History at the University of Frankfurt am Main since 1983.
Johannes Vermeer | Johannes Kepler | Johannes Gutenberg | Johannes Peter Müller | Johannes Ockeghem | Johannes Rau | Miriam Fried | Johannes Müller | Johannes Heesters | Johannes Zukertort | Johannes Meursius | Cornelis Johannes van Houten | Johannes Meyer | Johannes Itten | Johannes Blaskowitz | Johannes von Lahnstein | Johannes Mötsch | Johannes Hevelius | Johannes Ciconia | Johannes von Trapp | Johannes von Müller | Johannes Ullrich | Johannes Trithemius | Johannes Theodor Reinhardt | Johannes Magnus | Johannes Leimena | Johannes Ghiselin | Johannes Gad | Johannes Ewald | Johannes Diderik van der Waals |