@inproceedings{SIGIR-1971-Paola,
	author        = "Robert A. Di Paola",
	booktitle     = "{Proceedings of the ACM SIGIR Information Storage and Retrieval Symposium}",
	cdrom         = "SIGIR1971/P095.pdf",
	doi           = "10.1145/511285.511296",
	pages         = "95--104",
	publisher     = "{ACM}",
	title         = "{The Relational Data File and the Decision Problem for Classes of Proper Formulas}",
	year          = 1971,
}