@unpublished{publication-5690,
	author={Frey, Bruno S and Meier, Stephan},
	institution={University of Zurich},
	issn={1424-0459},
	number={No. 162},
	series={Working paper series / Institute for Empirical Research in Economics},
	title={"Social Comparisons and Pro-social Behavior - Testing "Conditional Cooperation" in a Field Experiment"},
	year=2003,
}