Elkan, Walter
The English Language Book Society ; Penguin Books, 1973
Buku Teks
Norton, George W., author
McGraw-Hill, 1993
Buku Teks
Slavin, Stephen, author
Richard D. Irwin, 1991
Buku Teks
Morgan, Theodore, author
Prentice-Hall, 1950
Buku Teks
Cairncross, Alec, author
Butterworth, 1960
Buku Teks