@inproceedings{PS-1981-Nielsen,
	author        = "Leif Sandegaard Nielsen",
	booktitle     = "{Proceedings of a Workshop on Program Specification}",
	doi           = "10.1007/3-540-11490-4_25",
	isbn          = "3-540-11490-4",
	pages         = "415--422",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Concurrency}",
	volume        = 134,
	year          = 1981,
}