1. Institute of Economic and Cultural Geography, Department of Geography, Leibniz-Universität Hannover, Hanover, Germany.
2. Institute for Employment Research, IAB North, Kiel, Germany
3. Empirical Labour Economics and Spatial Econometrics, Department of Economics, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
4. Institute for Employment Research, IAB Rhineland-Palatinate-Saarland, Saarbrucken, Germany.
5. Institute for Employment Research, IAB Bavaria, Nuremberg, Germany.