@book{12888,
	author = {Cohen, David,},
	title = {Precalculus with unit-circle trigonometry /},
	publisher = {West Pub. Co.,},
	year = {c1994.},
	address = {Minneapolis/St. Paul :},
	edition = {2nd ed.},
	note = {Includes index.},
	url = {http://www.loc.gov/catdir/enhancements/fy1515/93002612-b.html}
}