Guoren Wang Bing Sun Jianhua Lv Ge Yu RPE Query Processing and Optimization Techniques for XML Databases. 224-237 2004 19 J. Comput. Sci. Technol. 2 http://jcst.ict.ac.cn/cone/cone42.html#paper13 db/journals/jcst/jcst19.html#WangSLY04