Downie, R.S
Oxford University Press, 1994
Buku Teks
edited by Michael Parker
Routledge , 1999
Buku Teks
Edge, Raymond S., author
Cengage Learning, 2018
Buku Teks
Seedhouse, David, author
Sage Publications, 2019
eBooks
Garrett, Thomas M., author
Prentice-Hall, 2001
Buku Teks