@book {RP-93-56,
	title = {A new technique for finding a generating family of siphons, traps and st-components},
	volume = {674},
	year = {1993},
	pages = {126-147},
	publisher = {Springer-Verlag},
	organization = {Springer-Verlag},
	author = {J.M. Couvreur and M. Silva},
	editor = {G. Rozenberg}
}

