E.H. Carr, The Twenty Year's Crisis (London: Macmillan, 1962), p. 107.
2.
Hedley Bull, 'International Theory : The Case for the Classical Approach'. in K. Knorr and J. Rosenau (eds), Contending Approaches to International Politics (Princeton, NJ: Princeton Lniversity Press, 1966), pp. 20-38.
3.
Ibid, p. 22.
4.
Theda Skocpol, 'Wallerstein's World Capitalist System: A Theoretical and Historical Critique'. American Journal of Sociology (Vol. 82, No. 5, 1977), pp. 1075-90.