Group service in macaques (Macaca fuscata), capuchins (Cebus apella) and marmosets (Callithrix jacchus): a comparative approach to identifying proactive prosocial motivations
Journal of Comparative Psychology (2013) - Comment
pubmed: 22250970  doi: 10.1037/a0026392  issn: 1939-2087  issn: 0735-7036 

Judith Maria Burkart, Carel Van Schaik