Heping Wang Xiaobo Zhang Ashfaq A. Khokhar Efficient "Void" Handling in Contention-Based Geographic Routing for Wireless Sensor Networks. 663-667 2007 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2007.129 conf/globecom/2007 db/conf/globecom/globecom2007.html#WangZK07