@inproceedings{SIGMOD-1993-AbiteboulLUW,
	author        = "Serge Abiteboul and Georg Lausen and Heinz Uphoff and Emmanuel Waller",
	booktitle     = "{Proceedings of the 23rd ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD93/P032.PDF",
	doi           = "10.1145/170035.170044",
	pages         = "32--41",
	publisher     = "{ACM Press}",
	title         = "{Methods and Rules}",
	year          = 1993,
}