Barrett, Harold Clark External Organizations; Center for Adaptive Behavior and Cognition, Max Planck Institute for Human Development, Max Planck Society; External Organizations;
http://www.sscnet.ucla.edu/anthro/faculty/barrett/essentialism.pdf (Publisher version)
Barrett, H. C. (2001). On the functional origins of essentialism. Mind and Society, 2(3), 1-30.