1. Department of Agricultural Market Analysis, Institute of Agricultural Economics, Christian-Albrechts-University Kiel, Kiel, Germany
2. Leibniz-Institut für Agrartechnik und Bioökonomie e.V. (ATB), Potsdam, Germany
3. Department of Agricultural Economics, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
4. Department of Agricultural Economics, University of Zabol, Bonjar Ave, Zabol, Iran