London, 2004
Buku Teks
Euromonitor, 1989
Buku Teks
edited by Arthur S. Banks, Alan J. Day, Thomas C. Muller
CSA Publications, 1997
Buku Referensi
edited by Gary Hoover, Acta Campbell, Patrick J, Spain
The Reference Press, 1991
Buku Referensi
edit oleh Albert L. Hester, Wai Lan J. To
Yayasan Obor Indonesia, 1997
Buku Teks