Artikel Jurnal
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
Zenkovick, V., author
Foreign Languages Publishing House, 1958
Buku Teks