Clark, Anna
Rivers Oram , 1995
Buku Teks
Cole, G.D.H. (George Douglas Howard), 1889-1959
Methuen , 1956
Buku Teks
Banks, J. A.
Routledge & Kegan Paul Limited, 1954
Buku Teks
Trevelyan, George Macaulay, 1876-1962
Longmans, Green, 1950
Buku Teks
Longman, 1990
Buku Teks