1. Institute of Geography, Center for Regional Economic Development, University of Bern, Bern, Switzerland.
2. Institute of Geography, Center for Regional Economic Development, University of Bern, Bern, Switzerland; and Department of Geography, Umeå University, Umeå, Sweden.
3. Department of Geography, Umeå University, Umeå, Sweden; and Center for Regional Science, Umeå University, Umeå, Sweden.