1. Bertalanffy von L (1976) General system theory: Foundations, development, applications. New York: George Braziller.
2. Parsons T (1951) The social system. New York: Free Press.
3. Parsons T (1970) Social structure and personality. New York: Free Press.
4. Porpora DV (1987) The concept of social structure. New York: Greenwwod.
5. Crothers C (1996) Social structure. London: Routledge.