@book{55828,
	author = {Bortz, Jürgen and Döring, Nicola},
	title = {Forschungsmethoden und Evaluation für Human- und Sozialwissenschaftler },
	publisher = {Springer-Verlag},
	year = {2006},
	series = {Springer-Lehrbuch},
	address = {Berlin},
	note = {Literaturverz. S. 829 - 887},
	url = {http://d-nb.info/980731216/04}
}