Osgood, Cornelius
The University of Arizona Press, 1975
Buku Teks
John Wiley & Sons, 2014
Buku Teks
Clewlow, Carol, author
Lonely Planet, 1989
Buku Referensi
Reiber, Beth, author
Prentice-Hall, 1986
Buku Teks
Tan, Chwee Huat, author
Saw Centre Financial Studies, NUS Business School, 2007
Buku Teks