@book{190593,
	author = {Van Valkenburg, M. E.},
	title = {Analog filter design /},
	publisher = {Holt, Rinehart, and Winston,},
	year = {c1982.},
	address = {New York :},
	url = {http://www.loc.gov/catdir/enhancements/fy0640/81023774-d.html}
}