1. Researcher, Agrifood Chain Management Group, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin, Invaliden Str. 42, 10099 Berlin, Germany.
2. Senior Lecturer, Department of Agricultural Resource Economics, Jomo Kenyatta University of Agriculture and Technology, Kenya. P.O. Box 62000-00200, Nairobi, Kenya.
3. Full professor, Agrifood Chain Management Group, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin, Invaliden Str. 42, 10099 Berlin, Germany.