No costly prosociality among related long-tailed macaques (Macaca fascicularis)
Journal of Comparative Psychology (2015) - Comment
pubmed: 25961651  doi: 10.1037/a0039180  issn: 1939-2087  issn: 0735-7036 

Elisabeth H. M. Sterck, Caroline U. Olesen, Jorg J. M. Massen