References
- Elgin, C., and O. Oztunali. 2012. "Shadow Economies Around the World: Model-Based Estimates." Working Paper no. 2012/05, Bogazici University, Department of Economics, Istanbul.
- North, D.; J. J. Wallis; and B. R. Weingast. 2009. Violence and Social Orders: A Conceptual Framework for Interpreting Recorded Human History. Cambridge: Cambridge University Press.