edited by American Writing Corporation
The World Bank , 1996
Buku Teks
edited by Jacob A. Frenkel and Michael L. Mussa
Auburn House, 1984
Buku Teks
Paxton, John
Macmillan, 1976
Buku Referensi
edited by Richard Mann
Gateway Books, 2000
Buku Teks
edited by Miguel S. Wionczek
Frederick A. Praeger, 1966
Buku Teks