Bradford, Barbara
Cambridge University Press, 1988
Buku Teks
Hill, L.A.
Oxford University Press, 1982
Buku Teks
Hill, LA
Oxford University press, 1982
Buku Teks
Wiley Blackwell, 2014
Buku Teks
Hewings, Martin, author
Cambridge University Press, 2005
Buku Teks