@book{8088,
	author = {Elwood, J. Mark. and Elwood, J. Mark.},
	title = {Critical appraisal of epidemiological studies and clinical trials /},
	publisher = {Oxford University Press,},
	year = {1998.},
	address = {Oxford ;},
	edition = {2nd ed.},
	note = {Rev. ed. of: Causal relationships in medicine / J. Mark Elwood. 1988.},
	url = {http://www.loc.gov/catdir/enhancements/fy0605/97022473-d.html}
}