http://doi.acm.org/10.1145/248603.248608 db/journals/sigmod/RiekertMW97.html Wolf-Fritz Riekert Roland Mayer-Föll Gerlinde Wiest Management of Data and Services in the Environmental Information System (UIS) of Baden-Württemberg. 22-26 sigmodR/26-1/P022.pdf 1997 26 SIGMOD Record 1 db/journals/sigmod/sigmod26.html#RiekertMW97 http://www.acm.org/sigmod/record/issues/9703/Special/riekert.ps