Smith, David
Macmillan, 1995
Buku Teks
Macmillan, 1988
Buku Teks
Smith, Graeme Kinross
[Publisher not identified], [Date of publication not identified]
Buku Teks SO
Keller, Edward A.
Prentice-Hall, 1996
Buku Teks
Galsworthy, J Galsworthy, John
Melbourne [etc.] Heineman 1948
Buku Teks