1. Martin Wight, Systems of States ( Leicester: Leicester University Press, 1977 ), p. 127.
2. Herbert Butterfield, The Whig Interpretation of History ( New York: W.W. Norton Sr Company, 1965 ), p. 9.
3. Hedley Bull, ‘International Theory: The Case for a Classical Approach’, World Politics, XVIII (1966): 366–368.
4. Andrew Linklater and Hidemi Suganami, The English School of International Relations: A Contemporary Reassessment ( Cambridge: Cambridge University Press, 2006 ), pp. 87–88.
5. Herbert Butterfield, History and Human Relations (New York: Macmillan, 1952), pp. 12, 120.