Karin Leichtenstern Elisabeth André Thurid Vogt Role Assignment Via Physical Mobile Interaction Techniques in Mobile Multi-user Applications for Children. 38-54 2007 conf/eusai/2007 AmI http://dx.doi.org/10.1007/978-3-540-76652-0_3 db/conf/eusai/ami2007.html#LeichtensternAV07