1. Data cube: A relational aggregation operator generalizing group-by, cross-tab, and sub-total;Gray,1996
2. On the need of a reference algebra for OLAP;Romero,2007
3. Explaining differences in multidimensional aggregates;Sarawagi,1999
4. User-adaptive exploration of multidimensional data;Sarawagi,2000
5. Intelligent rollups in multidimensional OLAP data;Sathe,2001