A.  Monreale, Wang, H. Wendy, Pratesi, F., Rinzivillo, S., Pedreschi, D., Andrienko, G., and Andrienko, N., ?Privacy-Preserving Distributed Movement Data Aggregation?, in Geographic Information Science at the Heart of Europe, D.  Vandenbroucke, Bucher, B., and Crompvoets, J., Eds. Springer International Publishing, 2013, pp. 225-245.