@book{7713,
	author = {Little, Roderick J. A. and Rubin, Donald B.},
	title = {Statistical analysis with missing data /},
	publisher = {Wiley,},
	year = {c1987.},
	address = {New York :},
	url = {http://www.loc.gov/catdir/toc/onix04/86019075.html}
}