1. Sapolsky, R. A Primate's Memoir: A Neuroscientist's Unconventional Life Among the Baboons (Scribner, 2001).
2. Finlay, B. L., Darlington, R. B. & Nicastro, N. Behav. Brain Sci. 24, 263–308 (2001).
3. Gee, H. Nature 420, 611 (2002).
4. Berridge, K. C. in Handbook of Affective Sciences (eds Davidson, R. J., Scherer, K. R. & Goldsmith, H. H.) Ch. 3 (Oxford Univ. Press, 2003).