Bello, Walden F., author
Institute for Food and Development Policy, 1982
Buku Teks
White, Lawrence J.
Oxford University Press, 1991
Buku Teks
World Bank
New York Oxford University Press 1992,
Buku Referensi
Hayder, Joseph Ralston
Macmillan, 1950
Buku Teks
Baum, Warren C., author
Oxford University Press , 1985
Buku Teks