@inproceedings{SIGMOD-1988-YuanC,
	author        = "Li-Yan Yuan and Ding-An Chiang",
	booktitle     = "{Proceedings of the 18th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD88/P074.PDF",
	doi           = "10.1145/50202.50210",
	pages         = "74--81",
	title         = "{A Sound and Complete Query Evaluation Algorithm for Relational Databases with Null Values}",
	year          = 1988,
}