@book{9581,
	author = {Middlehurst, Jack. and Harrison, Roger.},
	title = {Practical filter design/book and disk /},
	publisher = {Prentice Hall,},
	year = {1993.},
	address = {[S.l.] :},
	edition = {Pap/Dis ed.},
	url = {http://www.amazon.com/exec/obidos/ASIN/0137199805/chopaconline-20}
}