@article {4006,
	title = {Implication Problems for Functional Constraints on Databases Supporting Complex Objects},
	journal = {Journal of Computer and System Sciences (JCSS)},
	volume = {50},
	year = {1995},
	pages = {165--187},
	doi = {10.1006/jcss.1995.1015},
	author = {Minoru Ito and Grant Weddell}
}
