Ingo F. Walther was born in Berlin and studied medieval studies, literature, and art history in Frankfurt am Main and Munich. He has published numerous books on the art of the Middle Ages and of the 19th and 20th centuries. He died on April 21, 2007.
Rainer Metzger is a writer and cultural historian, and professor of art history at the Academy of Karlsruhe, Germany. His books include "Vincent van Gogh: The Complete Paintings" (1996) and "Gustav Klimt: Drawings and Watercolors" (2005). He lives in Vienna.