Artikel Jurnal
Rivkin, Malcolm D., author
Frederick A. Praeger, 1965
Buku Teks
Bowett, D. W. (Derek William), author
Manchester University Press, 1967
Buku Teks
Churchill, R.R., author
Manchester University Press, 1992
Buku Teks
edited by Alan E. Ingham
John Wiley & Sons, 1975
Buku Teks