Weiwei Sun Ping Yu Yongrui Qin Zhuoyao Zhang Baihua Zheng Two-Tier Air Indexing for On-Demand XML Data Broadcast. 199-206 2009 ICDCS http://dx.doi.org/10.1109/ICDCS.2009.42 conf/icdcs/2009 db/conf/icdcs/icdcs2009.html#SunYQZZ09