Wilkes, Angela
Passport Books, 1987
Buku Teks SO
Rybak, Stephanie
Macmillan, 1985
Buku Teks SO
Barratt, William B.
Aldine House, 1994
Buku Teks
Spencer, R.A.
Edward Arnold, [Date of publication not identified]
Buku Teks SO
Skaife, Linda
National Textbook Company, 1994
Buku Teks SO