Birkha'user Verlag, 1997
Buku Teks
birkha'user Verlag, 1998
Buku Teks
MacMillan St Martin's Press, 1953
Buku Referensi
World, Bank, author
The International Bank for Reconstruction and Development, 1995,
Buku Referensi
edited by Brian Hunter
Macmillan, 1991
Buku Referensi