Gerold Ambrosius is retired Professor in economic and social history; studies in economics and political science, 1977 doctorate and 1983 habilitation; (visiting) professor at different German universities and abroad; main fields of research: economic history and institutional economics, history of public economy and public services, European economic history and integration. Christian Henrich-Franke is PD in economic and social history at the University of Siegen, studies in history and social sciences, 2005 doctorate and 2010 habilitation; main fields of research: international history, European integration, history of communications.