Thody, Philip, author
Routledge , 1997
Buku Teks
Thompson, June M., author
Westview Press, 1990
Buku Teks
Phinnemore, David, author
Routledge, Taylor & Francis Group, 2008
Buku Referensi
Nugent, Neill, author
Macmillan, 1994
Buku Teks
Oxford University Press, 2003
Buku Teks