Illenberger, J., Flötteröd, G., Kowald, M. and Nagel, K. (2009). A model for spatially embedded social networks. 12th Conference of the International Association for Travel Behaviour Research (IATBR)
Herrmann, H. J., Flekkoy, E., Nagel, K., Peng, G. and Ristow, G. (1994). Density waves in granular flow. Non-linearity and breakdown in soft condensed matter. Springer.