Tapio Niemi Jyrki Nummenmaa Peter Thanisch Logical Multidimensional Database Design for Ragged and Unbalanced Aggregation. 7 2001 conf/dmdw/2001 DMDW http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-39/paper7.pdf db/conf/dmdw/dmdw2001.html#NiemiNT01