@book{66730,
	author = {Elton, Edwin J. and Gruber, Martin Jay,},
	title = {Modern portfolio theory and investment analysis /},
	publisher = {Wiley,},
	year = {c1981.},
	address = {New York :},
	edition = {4th ed.},
	url = {http://www.loc.gov/catdir/toc/onix03/94042489.html}
}