Fairhead, J. N.
English Universities Press, 1965
Buku Teks
Williams, J. D., author
Little, Brown and Co., 1980
Buku Teks
Seeley, Harry W.
W H Freeman, 1972
Buku Teks
Giles, J. P.
Rigby, 1962
Buku Teks
McGivering, Ian C.
Liverpool University Press, 1960
Buku Teks