@book{44912,
	author = {Astrom, Karl J. and Wittenmark, Björn.},
	title = {Computer controlled systems  },
	publisher = {Prentice Hall },
	year = {c1997.},
	series = {Prentice Hall information and system sciences series.},
	address = {Upper Saddle River, N.J. },
	edition = {3a ed.}
}