1. Martin Berger is at the Institute of Technology and Regional Policy, Joanneum Research, Wiedner Hauptstrasse 76, A-1040 Wien, Austria,.
2. Javier Revilla Diez has a Chair of Economic Geography, Institute of Geography, Christian-Albrechts Universität Kiel, Ludewig-Meyn-Straße 14, 24098 Kiel, Germany,.