Handelman, Howard, author
Pearson/Prentice Hall, 2006
Buku Teks
Dixon, Chris J., author
Routledge, 2015
Buku Teks
Todaro, Michael P., author
Longman, 1992
Buku Teks
World Bank
Oxford University Press, 1991
Buku Teks
edited by P. Ebow Bondzi-Simpson
Praeger, 1992
Buku Teks