@inbook {ICEsSi90a,
	title = {Circuits, Handles, Bridges and Nets},
	booktitle = {Advances in Petri Nets 90},
	volume = {483},
	year = {1991},
	pages = {210-242},
	publisher = {Springer-Verlag},
	organization = {Springer-Verlag},
	address = {Berlin},
	author = {J. Esparza and M. Silva},
	editor = {G. Rozenberg}
}

