Ward, Russel, author
Macmillan, 1987
Buku Teks
Ward, Russel, author
Prentice-Hall, 1965
Buku Teks
Ward, Russel, author
Heinemann educational Australia, 1977
Buku Teks
McPhee-Gribble, 1988
Buku Teks
Crawford, R. M.
Hutchinson's University Library, 1955
Buku Teks