@book{1975,
	author = {Altman, Douglas G.},
	title = {Practical statistics for medical research /},
	publisher = {Chapman and Hall,},
	year = {1991.},
	address = {London ;},
	edition = {1st ed.},
	url = {http://www.loc.gov/catdir/enhancements/fy0646/91124890-d.html}
}