Mudhakar Srivatsa Arun Iyengar Jian Yin Ling Liu A Scalable Method for Access Control in Location-Based Broadcast Services. 256-260 2008 INFOCOM http://dx.doi.org/10.1109/INFOCOM.2008.60 conf/infocom/2008 db/conf/infocom/infocom2008.html#SrivatsaIYL08