Serge Abiteboul Sophie Cluet Tova Milo Correspondence and translation for heterogeneous data. 179-213 2002 275 Theor. Comput. Sci. 1-2 db/journals/tcs/tcs275.html#AbiteboulCM02 http://dx.doi.org/10.1016/S0304-3975(01)00128-1