@book{26,
	author = {Workshop Semigroups and Languages and Araújo, Isabel M. and Universidade de Lisboa.},
	title = {Semigroups and Languages :},
	publisher = {World Scientific,},
	year = {2004},
	address = {River Edge, NJ :},
	note = {Proceedings of workshop held at the Center of Algebra of the University of Lisbon.}
}