Having less, giving more: the influence of social class on prosocial behavior
Journal of Personality and Social Psychology (2010) - Comment
pubmed: 20649364  doi: 10.1037/a0020092  issn: 1939-1315  issn: 0022-3514 

Paul K. Piff, Michael W. Kraus, Stéphane Côté, Bonnie Hayden Cheng, Dacher Keltner