1. Social behaviour and adrenal cortical activity in heifers;Adeyemo;Appl. Anim. Ethol.,1982
2. Social hierarchy in the domestic goat: effect on food habits and production;Barroso;Appl. Anim. Behav. Sci.,2000
3. Bates, D., Maechler, M., Bolker, B., 2011. lme4: Linear mixed-effects models using S4 classes. R package version 0.999375-39. http://CRAN.R-project.org/package=lme4, last visited 22/03/2011.
4. Behavioral, cardiac and cortisol responses to brief peer separation and reunion in cattle;Boissy;Physiol. Behav.,1997
5. Model Selection and Multi-Model Inference;Burnham,2003