@inproceedings{SIGMOD-1990-LaenensSV,
	author        = "Els Laenens and Domenico Saccà and Dirk Vermeir",
	booktitle     = "{Proceedings of the 20th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD90/P184.PDF",
	doi           = "10.1145/93597.98728",
	pages         = "184--193",
	title         = "{Extending Logic Programming}",
	year          = 1990,
}