Rowthorn, Robert; Guzmán, Ricardo Andrés and Rodríguez-Sickert, Carlos (2008): The economics of early social stratification. Unpublished.
Rowthorn, Robert; Guzmán, Ricardo Andrés and Rodríguez-Sickert, Carlos (2011): The economics of social stratification in premodern societies. Unpublished.
Guzmán, Ricardo Andrés; Rodríguez-Sickert, Carlos and Rowthorn, Robert (2006): When in Rome, do as the Romans do: the coevolution of altruistic punishment, conformist learning, and cooperation. Published in: Evolution and Human Behavior , Vol. 28, No. 2 (March 2007): pp. 112-117.
