Yuzhen Li Jun Li Shuigeng Zhou GML Storage: A Spatial Database Approach. 55-66 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3289&spage=55 2004 conf/er/2004w ER (Workshops) db/conf/er/erw2004.html#LiLZ04