@INPROCEEDINGS{entailment-esop,
	author = "E. W. Stark",
	title = "Proving Entailment between Conceptual State Specifications",
	booktitle = "Proceedings of the 1986 European Symposium
			on Programming",
	city = "Saarbruecken, West Germany",
	publisher = "Springer-Verlag",
	series = "Lecture Notes in Theoretical Computer Science",
	volume = 213,
	month = mar,
	year = 1986,
	pages = "197--209"
}

@article{entailment-tcs,
	author = "E. W. Stark",
	title = "Proving Entailment between Conceptual State Specifications",
	journal = "Theoretical Computer Science",
	volume = 56,
	number = "1",
	pages = "135--154",
	year = 1988
}