Sutter, Matthias Max Planck Institute for Research on Collective Goods, Max Planck Society;
https://doi.org/10.1016/j.joep.2006.12.003 (Any fulltext)
Kugler, T., Bornstein, G., Kocher, M., & Sutter, M. (2007). Trust between individuals and groups: Groups are less trusting than individuals but just as trustworthy. Journal of Economic Psychology, 28, 646-657.