@inproceedings{VLDB-1989-Guting,
	author        = "Ralf Hartmut Güting",
	booktitle     = "{Proceedings of the 15th International Conference on Very Large Data Bases}",
	ee            = "http://www.vldb.org/conf/1989/P033.PDF",
	isbn          = "1-55860-101-5",
	pages         = "33--44",
	publisher     = "{Morgan Kaufmann}",
	title         = "{Gral: An Extensible Relational Database System for Geometric Applications}",
	year          = 1989,
}