Coultas, Barbara, author
Teach Yourself Books, 1990
Buku Teks
Bower, Malcolm
Hodder & Stoughton, 1977
Buku Teks
Kurbegov, Eliane
Mc Graw Hill, 2012
Buku Teks
Spencer, R. A.
Edward Arnold & Co, [date of publication not identified]
Buku Teks
Barratt, William B.
Aldine House, 1994
Buku Teks