Aaldering, H., Ten Velden, F. S.
, van Kleef, G. A., & De Dreu, C. K. W. (2018).
Parochial cooperation in nested intergroup dilemmas is reduced when it harms out-groups.
Journal of Personality and Social Psychology,
114(6), 909-923.
https://doi.org/10.1037/pspi0000125