Modden, David
New York, Twayne, 1964
Buku Teks
Hope, A.D. (Alec Derwent), 1907-2000, author
Oxford University Press, 1975
Buku Teks
Wright, M.R.
Routledge , 1996
Buku Teks
Wright, M.G., author
McGraw-Hill , 1970
Buku Teks
Wright, M.G., author
Tata McGraw-Hill, 1981
Buku Teks