He is the author of Aberglauben im 19. Jahrhundert. Preußen und seine Rheinprovinz zwischen Tradition und Moderne 1815–1918 (2003), and along with Diethard Sawicki is currently editing Entzauberte Moderne?, a collection of essays on the occult in nineteenth- and twentieth-century Europe. His research interests include the social, cultural and environmental history of Germany in the eighteenth and nineteenth centuries.