Campadello, S.; Coutand, O.; vanEijk, P. E. R.; Hjelm, J.; Holtmanns, S.; Kanter, T.; Lau, S. L.; Martin, M.; Melén, B.; Miettinen, M.; Nani, R.; Nurmi, P.; Radziszewski, M.; Salacinski, M.; Schultz, G. & Turtiainen, E. (2007), Enabling Technologies for Mobile Services: The MobiLife Book , John Wiley & Sons , chapter 6. Privacy, Trust and Group Communications .