Karin Leichtenstern Alexander De Luca Enrico Rukzio Analysis of Built-in Mobile Phone Sensors for Supporting Interactions with the Real World. 31-34 2005 conf/pervasive/2005id PERMID http://www.medien.ifi.lmu.de/permid2005/pdf/KarinLeichtenstern_Permid2005.pdf db/conf/pervasive/permid2005.html#LeichtensternLR05