The Köhler effect: Motivation gains and losses in real sports groups
Sport Exercise and Performance Psychology (2012) - Comment
doi: 10.1037/a0026887  issn: 2157-3913  issn: 2157-3905 

Kaitlynn A. Osborn, Brandon C. Irwin, Nikolaus J. Skogsberg, Deborah L. Feltz