The World Bank, 1993
Buku Teks
Aswathanarayana, U., author
A.A. Balkema, , 2001
Buku Teks
Saunders, Robert J.
The John Hopkins University Press , 1976
Buku Teks
Washington The World Bank 1993,
Buku Teks
Chaturvedi, M.C.
Tata McGraw-Hill, 1987
Buku Teks