http://doi.acm.org/10.1145/234889.234901 db/journals/sigmod/Colliat96.html George Colliat OLAP, Relational, and Multidimensional Database Systems. 64-69 sigmodR/25-3/P064.pdf 1996 25 SIGMOD Record 3 db/journals/sigmod/sigmod25.html#Colliat96