@book{13208,
	author = {Lef,Edward and Leff, Edward.},
	title = {Introduction to feedback control systems /},
	publisher = {McGraw-Hill Companies,},
	year = {1979.},
	address = {London :},
	url = {http://www.amazon.com/exec/obidos/ASIN/007019310X/chopaconline-20}
}