@book{2257,
	author = {Mason, Robert D.  and Hermanson, Roger H. },
	title = {Programmed learning aid for business and economic statistics /},
	publisher = {Learning Systems, },
	year = {c1978.},
	series = {Irwin Programmed learning aid series.},
	address = {Homewood, Ill. :},
	note = {Includes index.}
}