Susan Darling Urban Anton P. Karadimce Suzanne W. Dietrich Taoufik Ben Abdellatif Hon Wai Rene Chan 67-111 1997 22 Data Knowl. Eng. 1 db/journals/dke/dke22.html#UrbanKDAC97 http://dx.doi.org/10.1016/S0169-023X(96)00041-9