D. Davison, и G. Graefe. SIGMOD '95: Proceedings of the 1995 ACM SIGMOD international conference
on Management of data, стр. 281--292. New York, NY, USA, ACM, (1995)
S. Freyer, J. Graefe, M. Heinzel, и P. Marenbach. Eufit '98, 6th European Congress on Intelligent
Techniques and Soft Computing, ELITE - European
Laboratory for Intelligent TechniquesEngineering, III, стр. 1471--1475. Aachen, Germany, (1998)