Phinnemore, David, author
Routledge, Taylor & Francis Group, 2008
Buku Referensi
Oxford University Press, 2003
Buku Teks
McCauley, Martin
Longman, 1993
Buku Teks
Folsom, Ralph Haughwout, author
West Group, 1995
Buku Teks
El-Agraa, Ali M, author
Prentice-Hall, 2001
Buku Teks