Yanlei Diao Daniela Florescu Donald Kossmann Michael J. Carey Michael J. Franklin Implementing Memoization in a Streaming XQuery Processor. 35-50 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3186&spage=35 2004 conf/xsym/2004 XSym db/conf/xsym/xsym2004.html#DiaoFKCF04