Alain Cohn, Ernst Fehr and Lorenz Goette, «Fairness and Effort – Evidence from a Field Experiment», Working Paper, October 2008; и Alain Cohn, Ernst Fehr, Benedikt Herrmann and Frederic Schneider, «Social Comparison in the Workplace: Evidence from a Field Experiment», IZA Working Paper 5550, март 2011 года.
