Adams, Thomas F.
Prentice-Hall, 1980
Buku Teks
Davies, Malcom, author
Longman, 1995
Buku Teks
Bachman, Ronet, author
McGraw-Hill, 2008
Buku Teks
Joyce, Peter, author
Routledge, 2018
Buku Teks
Roberts,Julian V, author
Open University Press, 2005
Buku Teks