@book{41896,
	author = {Pevalin, David J. and Robson, Karen. and ebrary, Inc.},
	title = {The Stata survival manual},
	publisher = {Open University Press,},
	year = {2009.},
	address = {Maidenhead, Berkshire :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10350202}
}