Arnon Amir Alon Efrat Jussi Myllymaki Lingeshwaran Palaniappan Kevin Wampler Buddy tracking - efficient proximity detection among mobile friends. 489-511 2007 3 Pervasive and Mobile Computing 5 http://dx.doi.org/10.1016/j.pmcj.2006.12.002 db/journals/percom/percom3.html#AmirEMPW07