@book{37184,
	author = {Littell, Julia H. and Corcoran, Jacqueline.},
	title = {Systematic reviews and meta-analysis},
	publisher = {Oxford University Press,},
	year = {2008.},
	series = {Pocket guides to social work research methods},
	address = {Oxford :},
	url = {http://dx.doi.org/10.1093/acprof:oso/9780195326543.001.0001}
}