Ubbels, B., Rietveld, P., Evangelinos, C., Wieland, B., Hoffmann, J., Schade, J., Bonsall, P., Matthews, B., de Rus, G., Betancor, O., Socorro, P., Jiménez, J. L., Božičnik, S., Letnik, T., Martino, A., Fiorello, D., Guelfi, M., Bielefeldt, C., Baird, A., & Wilmsmeier, G. (2007). DIFFERENT user reaction and efficient differentiationof charges and tolls: current status of differentiated charges for transport infrastructure use. Deliverable D2.1