@article {2112,
	title = {Social Comparisons and Pro-Social Behavior: Testing {\textquoteright}Conditional Cooperation{\textquoteright} in a Field Experiment},
	journal = {The American Economic Review},
	volume = {94},
	year = {2004},
	pages = {1717-1722},
	author = {Frey, Bruno S. and Meier, Stephan}
}
