An examination of the stability and persistence of the Köhler motivation gain effect
Group Dynamics Theory Research and Practice (2008) - Comment
doi: 10.1037/1089-2699.12.4.279  issn: 1930-7802  issn: 1089-2699 

Robert B. Lount, Norbert L. Kerr, Lawrence A. Messé, Dong-Heon Seok, Ernest S. Park