World Bank
New York Oxford University Press 1992,
Buku Referensi
White, Lawrence J.
Oxford University Press, 1991
Buku Teks
Hayder, Joseph Ralston
Macmillan, 1950
Buku Teks
Baum, Warren C.
Oxford University Press , 1985
Buku Teks
Harriss, John
Left world, 2001
Buku Teks