Yunxin Liu Ahmad Rahmati Yuanhe Huang Hyukjae Jang Lin Zhong Yongguang Zhang Shensheng Zhang xShare: supporting impromptu sharing of mobile phones. 15-28 2009 MobiSys http://doi.acm.org/10.1145/1555816.1555819 conf/mobisys/2009 db/conf/mobisys/mobisys2009.html#LiuRHJZZZ09