@book{129997,
	author = {Black, Thomas R. and ebrary, Inc.},
	title = {Understanding social science research},
	publisher = {Sage,},
	year = {2002.},
	address = {London ;},
	edition = {2nd ed.},
	note = {Previous ed.: 1993.},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10218280}
}