Andrews, Richard B., author
The Free Press, 1971
Buku Teks
El-Agraa, Ali M, author
Prentice-Hall, 2001
Buku Teks
Jha, Prabhat, author
World Bank, 1999
Buku Teks
Jha, Prabhat, author
World Bank, 1999
Buku Teks
McGuire, Mark F., author
University of Minnesota, 1989
Buku Teks