Bernd Wondergem Patrick van Bommel Theo P. van der Weide Cumulative Duality in Designing Information Brokers. 125-134 http://link.springer.de/link/service/series/0558/bibs/1460/14600125.htm 1998 conf/dexa/1998 DEXA db/conf/dexa/dexa98.html#WondergemBW98