@book{36655,
	author = {Elwood, J. Mark.},
	title = {Critical appraisal of epidemiological studies and clinical trials},
	publisher = {Oxford University Press,},
	year = {2007.},
	address = {Oxford :},
	edition = {3rd ed.},
	note = {Previous ed.: 1998.},
	url = {http://dx.doi.org/10.1093/acprof:oso/9780198529552.001.0001}
}