Susan B. Davidson Wenfei Fan Carmem S. Hara Propagating XML constraints to relations. 316-361 2007 73 J. Comput. Syst. Sci. 3 http://dx.doi.org/10.1016/j.jcss.2006.10.022 db/journals/jcss/jcss73.html#DavidsonFH07