@book{13327,
	author = {Greenberg, Marvin J. and Harper, John R.},
	title = {Algebraic topology :},
	publisher = {Westview Press,},
	year = {1981.},
	series = {Mathematics lecture note series.},
	address = {[S.l.] :},
	url = {http://www.amazon.com/exec/obidos/ASIN/0805335579/chopaconline-20}
}