Butterworth Legal Publishers, 1994
Buku Referensi
Butterworth Legal Publishers, 1994
Buku Referensi
Irving, John
Pocket Books, 1981
Buku Teks
editor, A.H. McLintock
R. E. Owen, Government printer, 1966
Buku Referensi
Encyclopaedia Britannica Inc., 2003
Buku Referensi