Alain Ketterlin Pierre Gançarski Jerzy J. Korczak Conceptual Clustering in Structured Databases: A Practical Approach. 180-185 1995 conf/kdd/1995 KDD db/conf/kdd/kdd95.html#KetterlinGK95 http://www.aaai.org/Library/KDD/1995/kdd95-020.php