@unpublished{publication-5838,
	author={Fehr, Ernst and Schmidt, Klaus M},
	institution={University of Zurich},
	issn={1424-0459},
	number={No. 20},
	series={Working paper series / Institute for Empirical Research in Economics},
	title={Fairness, Incentives, and Contractual Choices},
	year=1999,
}