Botella, J., García Leal, Óscar, Moreno, L., Pei-Chun, S. and Santacreu, J. 2011. An experimental study of coperation in a natural seting. Mexican Journal of Behavior Analysis. 31, 2 (Jan. 2011), 261–281. DOI:https://doi.org/10.5514/rmac.v31.i2.23250.