Chevalier, A. Max Planck Institute for Research on Collective Goods, Max Planck Society;
https://dx.doi.org/10.1080/13504851.2017.1400648 (Any fulltext)
Anderberg, D., Cerrone, C., & Chevalier, A. (2018). Soft commitment: a study on demand and compliance. Applied Economics Letters, 25(16), 1140-1146.