Bowett, D.W. (Derek William)
Manchester University Press, 1967
Buku Teks
Churchill, R.R.
Manchester University Press, 1992
Buku Teks
Mankabady, Samir
Elsevier, 1987
Buku Teks
Colombus, C. John
Longmans, 1959
Buku Teks
Booth, Ken
George Allen and Unwin, 1985
Buku Teks