Gregg, Pauline, author
George G. Harrap, 1967
Buku Teks
Seden, Janet, author
Open University Press, 2005
Buku Teks
Sullivan, Michael, author
Harvester Wheatsheaf, 1994
Buku Teks
Routledge, 1998
Buku Teks
Haley, Elie, author
Pelican Book, 1937
Buku Referensi