Hengyu Long Yongpan Liu Xiaoguang Fan Robert P. Dick Huazhong Yang Energy-efficient spatially-adaptive clustering and routing in wireless sensor networks. 1267-1272 2009 DATE http://ieeexplore.ieee.org/xpls/abs_all.jsp?isnumber=5090609&arnumber=5090860&count=326&index=246 conf/date/2009 db/conf/date/date2009.html#LongLFDY09