Aleksander Pivk Philipp Cimiano York Sure Matjaz Gams Vladislav Rajkovic Rudi Studer 567-595 2007 60 Data Knowl. Eng. 3 http://dx.doi.org/10.1016/j.datak.2006.04.002 db/journals/dke/dke60.html#PivkCSGRS07